Proving and identity with the normalized sine function
4644
Finding the limit $\lim \limits_{n \to \infty}\ (\cos \frac x 2 \cdot\cos \frac x 4\cdot \cos \frac x 8\cdots \cos \frac x {2^n}) $
35244
Prove $\sin^2\theta + \cos^2\theta = 1$
116580
Prove by induction: $\sin{x}+\sin{3x}+\dots+\sin{(2n-1)x}=\frac{\sin^2{nx}}{\sin{x}}$
109648
Proving an identity for Bernoulli polynomials
77253
Proof of Lagrange Identity
143857
How to prove absolute summability of sinc function?
107067
Finding the argument of $z=1-\cos(2\theta)-i\sin(2\theta)$
48394
Proving bessel identity $[J_0(x)]^2 + 2[J_1(x)]^2 + 2[J_2(x)]^2 + \cdots = 1$ and $|J_0(x)|\le 1$
116270
Functional equations leading to sine and cosine
7712
How to prove the both identity (matrix)
100788
Proving Newton's identities
18967
Linear independence of $\sin(x)$ and $\cos(x)$
30882
Proving Invertibility and Eigenvalues
123136
Proof of the identity: $c\sin \frac{A-B}{2} \equiv (a-b) \cos \frac{C}{2}$
53307
how to strictly prove $\sin x<x$ for $0<x<\frac{\pi}{2}$
145500
Finite Series - reciprocals of sines
34070
Agreed upon domain of inverse trig functions