How to rewrite $a\sin x+b\cos x$ just using $\sin x$ or $\cos x$?
55436
Why does $A\sin{k(x+c)}=a\sin{kx}+b\cos{kx}$ imply that $A=\sqrt{a^2+b^2}$ and $\tan{c}=-b/a$?
148632
How to expand $\cos nx$ with $\cos x$?
84730
use the fact that $\tan 2x=\sin2x \ /\cos2x$ to prove that $\tan 2x=2\tan x/(1-\tan^2x)$
7296
Prove $(1-\cos x)/\sin x = \tan x/2$
116270
Functional equations leading to sine and cosine
40235
How would I differentiate $\sin{x}^{\cos{x}}?$
148624
Replacing Tan[x] with Sin[x]/Cos[x]
111102
Prove the Trigonometric Identity: $\frac{\sin x}{1-\cos x} = \frac{1+\cos x}{\sin x}$
131688
Solve $\sin 7x+\sin 3x=0$
77978
Show that $\frac {\sin x} {\cos 3x} + \frac {\sin 3x} {\cos 9x} + \frac {\sin 9x} {\cos 27x} = \frac 12 (\tan 27x - \tan x)$
143070
If $\sin A + \cos A + \tan A + \cot A + \sec A + \csc A = 7$ then $x^2 - 44x - 36 = 0$ holds for $x=\sin 2A$
123476
Prove $[\sin x]' = \cos x$ without using $\lim\limits_{x\to 0}\frac{\sin x}{x} = 1$
145463
How to factorise $2 \sin^2θ – 3\sinθ +1 = 0$
57750
Solve identity: $\frac {\sin x}{1-\cos x} = \frac {1+\cos x}{\sin x}$
54512
How do I prove: $\cos (\theta + 90^\circ) \equiv - \sin \theta $
77810
Solving Trigonometric Derivatives
91521
Ambiguity of notation: $\sin(x)^2$