Proving cosines product identity
115733
Proving that $\sec\frac{\pi}{11}\sec\frac{2\pi}{11}\sec\frac{3\pi}{11}\sec\frac{4\pi}{11}\sec\frac{5\pi}{11}=32$
54175
Prove the trigonometric identity $\sin^4{x} = \frac{3-4\cos{2x}+\cos{4x}}{8}$
61483
Prove the following identity combinatorially
33104
Combinatorial Proof with Summation Identity
281
How one can prove $\prod_{k=1}^{n-1} (\cos\theta-\cos(k\pi/n)) = 2^{1-n}\sin(n\theta)\csc\theta$?
37040
Prove reduction formula for $\int \cos^n (x)\sin^m (x) \, dx$
126574
Proving $\prod_k \sin \pi k / n = n / 2^{n-1}$
24656
Proving that $\frac{\csc\theta}{\cot\theta}-\frac{\cot\theta}{\csc\theta}=\tan\theta\sin\theta$
93085
How to prove the identity $\prod_{n=1}^{\infty} (1-q^{2n-1}) (1+q^{n}) =1 $ for $|q|<1$?
141787
Anybody know a proof of $\prod_{n=1}^\infty\cos(x/2^n)=\sin x/x$.
26501
Proof using complex numbers
149686
Combinatorics and trigonometry identity
54512
How do I prove: $\cos (\theta + 90^\circ) \equiv - \sin \theta $
11335
Proving Binomial Identity without calculus
60761
Proof: $\cos^p (\theta) \le \cos(p\theta)$
77587
Cross product: matrix transformation identity
143540
How to prove this decomposition of sum of squares?