Mathematica Stack Exchange is a question and answer site for users of Mathematica. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am trying to find an explicit solution to a trigonometric equation. It is running for a long time and I didn't get any result, but Maple solves it quickly. Why ?

Solve[ γ == ArcCos[ Cos[α] Sec[θ] ] + ArcCos[ Cos[β] Sec[θ] ], θ]
share|improve this question
If you're looking for a numeric solution please say so explicitly. – b.gatessucks Sep 23 '12 at 10:52
up vote 5 down vote accepted

If you're after a symbolic solution you might try taking the Cos of both sides :

Solve[ Cos[ γ] == TrigExpand[ Cos[ ArcCos[ Cos[α] Sec[θ] ] + ArcCos[ Cos[β] Sec[θ]] ]],
         θ, Reals]


Reduce[ Cos[γ] == TrigExpand[  Cos[ ArcCos[ Cos[α] Sec[θ] ] + ArcCos[ Cos[β] Sec[θ]]] ],
        θ, Reals] 
share|improve this answer
@chyanog You still didn't say, does the other software solve your equation symbolically ? – b.gatessucks Sep 23 '12 at 15:26

Or like this:

Solve[Cos /@ (γ == ArcCos[Cos[α] Sec[θ]] + ArcCos[Cos[β] Sec[θ]] ), θ, 
 InverseFunctions -> True]
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.