Proving Trig. Identities
48586
Prove: $\cot x=\sin x\,\sin\left(\frac{\pi}{2}-x\right)+\cos^2x\,\cot x$
10289
Need help in proving that $\frac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} = \frac 1{\sec\theta - \tan\theta}$
41943
Why is it that when proving trig identities, one must work both sides independently?
54512
How do I prove: $\cos (\theta + 90^\circ) \equiv - \sin \theta $
79686
How can I prove these statements?
46353
Proof that $\cos(\pi/3)=1/2$
96388
Prove $\sin(x)\tan(x) > x^2$ for $x \in ( \,0, \frac{\pi}{2}) \,$
106355
How to prove Lagrange trigonometric identity
141645
Trigonometric series sum proof
1859
Proving $\arctan(\sqrt{x^2+1}-x)=\frac{\pi}{4}-\frac{1}{2}\arctan(x)$
11335
Proving Binomial Identity without calculus
7712
How to prove the both identity (matrix)
100895
Prove $1 + \cos 2C - \cos 2A - \cos 2B = 4\sin A\sin B\cos C$ for $A$, $B$, $C$ the angles of a triangle
12741
How to prove that: $\tan(3\pi/11) + 4\sin(2\pi/11) = \sqrt{11}$
17769
Show that $\frac{\sin x}{\cos 3x}+\frac{\sin 3x}{\cos 9x}+\frac{\sin 9x}{\cos 27x} = \frac{1}{2}\left(\tan 27x-\tan x\right)$
77253
Proof of Lagrange Identity
32197
Prove that $\tan A + \tan B + \tan C = \tan A\tan B\tan C,$ $A+B+C = 180^\circ$