why $ 1 - \cos^2x = \sin^2x $?
35244
Prove $\sin^2\theta + \cos^2\theta = 1$
2648
Show that the equation $\cos(\sin x)=\sin(\cos x)$ has no real solutions.
141787
Anybody know a proof of $\prod_{n=1}^\infty\cos(x/2^n)=\sin x/x$.
120444
Trigonometric Triangle Equality
48086
Why is this series of square root of twos equal $\pi$?
32792
Proving: $\cos A \cdot \cos 2A \cdot \cos 2^{2}A \cdot \cos 2^{3}A ... \cos 2^{n-1}A = \frac { \sin 2^n A}{ 2^n \sin A } $
43605
If $\sin(a)\sin(b)\sin(c)+\cos(a)\cos(b)=1$ then find the value of $\sin(c)$
107067
Finding the argument of $z=1-\cos(2\theta)-i\sin(2\theta)$
118586
Confused About Trigonometric Substitution
281
How one can prove $\prod_{k=1}^{n-1} (\cos\theta-\cos(k\pi/n)) = 2^{1-n}\sin(n\theta)\csc\theta$?
128258
Why aren't the graphs of $\sin(\arcsin x)$ and $\arcsin(\sin x)$ the same?
46665
Solving $\cos x+\sin x-1=0$
94283
Different ways finding the derivative of $\sin$ and $\cos$.
127380
Use vectors to prove $\cos(\beta - \alpha) = \cos \alpha \cos\beta + \sin\alpha \sin\beta$
122705
Solution of trigonometric equation $0 = x\cos(x)+2$
123136
Proof of the identity: $c\sin \frac{A-B}{2} \equiv (a-b) \cos \frac{C}{2}$
9986
Prove $ \sin(A+B)\sin(A-B)=\sin^2A-\sin^2B $