I was working on a problem involving trigonometry. I used Mathematica to help me in solving it. I ended up with this formula:
-(1/R) Csc[a - 2 b] (R Cos[a - 2 b] - R (Cos[a - 2 b] - Cot[2 a - 2 b] Sin[a - 2 b]))* (-R + R Sin[a - 2 b] - (R^2 Cos[a - 2 b] Sin[a - 2 b])/(R Cos[a - 2 b] - R (Cos[a - 2 b] - Cot[2 a - 2 b] Sin[a - 2 b])))
And I know that $\sin a = n\times\sin b $ where $n$ is a real number. After this I expanded the formula using
TrigExpand that generated a very large output. I want to know how I can replace all trigonometric functions that contains $b$ so at the end I have a formula that contains just $n$ and trigonometric functions that have $a$.