Trig proof using complex numbers
129890
Proving inequality $|\sin(n\theta) |\le n\sin\theta$
81571
Complex Exponent of Complex Numbers
141645
Trigonometric series sum proof
18005
Angle notation for complex numbers in polar form
44119
Prove that $\cos (A + B)\cos (A - B) = {\cos ^2}A - {\sin ^2}B$
60559
How prove this $x^3<\sin^2{x}\tan{x},x\in\left(0,\dfrac{\pi}{2}\right)$
96328
Proving $e^{i\pi} = -1$ without proving $e^{ix} = \cos x + i\sin x$
54175
Prove the trigonometric identity $\sin^4{x} = \frac{3-4\cos{2x}+\cos{4x}}{8}$
116206
Complex number question on proving an inequality.
34049
How can I understand and prove the "sum and difference formulas" in trigonometry?
13297
Prove the following trigonometric identity without a calculator involved
40596
Proving a relation between inradius ,circumradius and exradii in a triangle
138575
Proof that $\cos^2(x)\cosh^2(y) + \sin^2(x)\sinh^2(y) = -1 + \sin^2(x) - \sinh^2(y)$
7296
Prove $(1-\cos x)/\sin x = \tan x/2$
71413
Proving complex series $1 + \cos\theta + \cos2\theta +... + \cos n\theta $
33396
Generalizing a Trig Identity
15237
Prove an inequality using complex analysis