# Simplification of long trigonometric expression taking a long time

I have tried to Simplify as well as FullSimplify a long trigonometric expression to get a simplified form of the expression but it takes a very long time almost hours and sometimes it also shows error as 'Exceeding time constraint more than 300 seconds'. Please suggest how can we solve this and get the simplified form of the expression. And if if there any other way to simplify trigonometric expression please suggest. Is there any way to shorten the run time and get the output quickly. Here is the trigonometric expression which we want to simplify

 2 Cos[Subscript[\[Theta], 12]]^4 Cos[2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^4 Cos[Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 13]]^2 -
2 Cos[Subscript[\[Theta], 12]]^4 Cos[2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^4 Cos[Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 13]]^2 +
2 Cos[Subscript[\[Theta], 12]]^4 Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^4 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 13]]^2 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 23]]^4 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]]^4 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^4 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^4 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta], 23]]^3 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]] +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^3 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]] -
4 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[Subscript[\[Theta],
23]]^3 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] +
4 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[ 2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] +
4 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] -
4 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^4 Cos[
Subscript[\[Theta], 23]]^3 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]] -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^4 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]] -
2 Cos[Subscript[\[Theta], 12]]^3 Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^3 Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]] +
2 Cos[Subscript[\[Theta], 12]]^3 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]] +
2 Cos[Subscript[\[Theta], 12]]^3 Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^3 Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]] -
2 Cos[Subscript[\[Theta], 12]]^3 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^3 Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]] -
4 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]]^2 Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]] +
4 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]] +
4 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]] -
4 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]] +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^4 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^4 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^2 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^4 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] - Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^4 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] -
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^4 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] -
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^4 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] -
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^4 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]] -
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^4 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 23]]^2 -
2 Cos[Subscript[\[Theta], 12]]^3 Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]] Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
23]]^2 +
2 Cos[Subscript[\[Theta], 12]]^3 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]] Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^3 Cos[Subscript[\[Theta], 23]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^3 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]] Sin[Subscript[\[Theta], 12]]^3 Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^3 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Sin[Subscript[\[Theta], 12]]^3 Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^3 Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 23]] Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^3 Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^3 Sin[Subscript[\[Theta], 13]] Sin[Subscript[\[Theta],
23]]^2 -
2 Cos[\[Delta]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^3 Sin[Subscript[\[Theta], 13]] Sin[Subscript[\[Theta],
23]]^2 +
2 Cos[\[Delta]] Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta],
23]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta], 12]]^3 Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^2 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^2 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^2 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^2 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^3 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta],
23]]^2 Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^2 +
2 Cos[Subscript[\[Theta], 12]]^3 Cos[Subscript[\[Theta], 23]]^2 Cos[
Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]] Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]]^2 Sin[Subscript[\[Theta], 23]]^2 -
2 Cos[Subscript[\[Theta], 12]]^3 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]]^2 Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]] Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]]^2 Sin[Subscript[\[Theta], 23]]^2 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^3 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^3 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Mu]]] Cos[Subscript[\[Phi], \[Tau]]] Sin[
Subscript[\[Theta], 12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta],
23]] Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta],
23]] Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]] Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]]^2 Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]] Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta],
23]] Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]] Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta],
23]] Cos[\[Delta] + Subscript[\[Phi], \[Mu]]] Cos[
Subscript[\[Phi], \[Tau]]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta],
13]] Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]] Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 12]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^3 -
2 Cos[Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^3 +
2 Cos[Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 12]] Cos[
2 Subscript[\[Theta], 13]] Sin[\[Delta]]^2 Sin[Subscript[\[Theta],
12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta],
23]]^3 -
2 Cos[Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]] Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[Subscript[\[Theta], 12]] Cos[2 Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]] Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]]^2 Sin[
Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 13]] Cos[
Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 +
2 Cos[Subscript[\[Theta], 12]]^2 Cos[Subscript[\[Theta], 13]] Cos[
2 Subscript[\[Theta], 13]] Cos[Subscript[\[Theta], 23]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]] Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^3 -
2 Cos[\[Delta]]^3 Cos[Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^4 +
2 Cos[\[Delta]]^3 Cos[Subscript[\[Theta], 12]] Cos[
Subscript[\[Theta], 13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[Subscript[\[Theta], 12]]^2 Sin[
2 Subscript[\[Theta], 12]] Sin[Subscript[\[Theta], 13]] Sin[
Subscript[\[Theta], 23]]^4 -
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[Subscript[\[Theta],
13]] Cos[Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^4 +
2 Cos[\[Delta]] Cos[Subscript[\[Theta], 12]] Cos[Subscript[\[Theta],
13]] Cos[2 Subscript[\[Theta], 13]] Cos[
Subscript[\[Phi], \[Tau]]]^2 Sin[\[Delta]]^2 Sin[
Subscript[\[Theta], 12]]^2 Sin[2 Subscript[\[Theta], 12]] Sin[
Subscript[\[Theta], 13]] Sin[Subscript[\[Theta], 23]]^4 +
2 Cos[\[Delta]]^2 Cos[Subscript[\[Theta], 12]]^2 Cos[
2 \[Delta] + Subscript[\[Phi], \[Mu]] -
Subscript[\[Phi], \[Tau]]] Sin[Subscript[\[Theta], 12]]^2 Sin[
Subscript[\[Theta], 13]]^2 Sin[Subscript[\[Theta], 23]]^4 

• Copy and paste your code correctly. There is some error. Apr 20 at 8:40
• See if its coming correctly now. Apr 20 at 8:58
• Simplify your expressions at each step, do not wait until outputs get too complicated to be easily simplified. Your expression is very long and complex and has lots of variables so it is not a surprise it takes a long time to be simplified. Also it is better to use x17 instead of Subscript[x, 17]. Try to avoid using Subscript. Apr 20 at 9:49
• Do you know there is a particular simplification in that result that you know should be done? Like expr1*Sin[expr2]^2+expr1*Cos[expr2]^2 == expr1? Or are you just thinking that it should somehow be five times simpler and so Mathematica should try every possible simplification idea it has all 4630 symbols in that and do all that in 20 seconds? If you know it is the first then it may be possible, maybe not, to try something like hugeexpression//.expr1_*Sin[expr2_]^2+expr1_*Cos[expr2_]^2->expr1` and carefully check to see if that worked or not. I quickly got a 23% smaller result with that.
– Bill
Apr 20 at 17:41