How does (cosx+isinx)^4 equate to 1-8 cos^2(x)+8 cos^4(x)-4 i cos(x) sin(x)+8 i cos^3(x) sin(x)
1210
Write an expression for $(\cos θ + i\sin θ)^4$ using De Moivre’s Theorem.
16866
How to Prove $a^3 \cos (B-C) + b^3 \cos (C-A)+ c^3 \cos (A-B)=3abc$?
83332
Trig sum: $\tan ^21^\circ+\tan ^22^\circ+\cdots+\tan^2 89^\circ = \text{?}$
31852
An elegant way to solve $\frac {\sqrt3 - 1}{\sin x} + \frac {\sqrt3 + 1}{\cos x} = 4\sqrt2 $
57750
Solve identity: $\frac {\sin x}{1-\cos x} = \frac {1+\cos x}{\sin x}$
51729
Solve the following equation: $\sqrt {\sin x - \sqrt {\cos x + \sin x} } = \cos x$
17168
Find the value of $\sin\frac{2\pi}{7}+\sin\frac{4\pi}{7}+\sin\frac{8\pi}{7}$
55179
How to find the exact value of $ \cos(36^\circ) $?
101448
Is $\sin^2(z) + \cos^2(z)=1$ still true for $z \in \Bbb{C}$?
29370
Trig integral $\int ( \cos{x} + \sin{x}\cos{x}) \, dx $
45343
Solve $\cos^{n}x-\sin^{n}x=1$ with $n\in \mathbb{N}$.
115128
How do I show this $\cos^2(\arctan(x))=\frac{1}{1+x^2}$
38705
Evaluating $\sqrt{1 + \sqrt{2 + \sqrt{4 + \sqrt{8 + \ldots}}}}$
76490
Proving that $\cos(\arcsin(x))=\sqrt{1-x^2}$
135774
Alternating roots of $f(x) = \exp(x) \sin(x) -1$ and $\exp(x)\cos(x) +1$
44438
Prove : $\frac{\cos(x_1) +\cos(x_2) +\cdots+\cos(x_{10})}{\sin(x_1) +\sin(x_2) +\cdots+\sin(x_{10})} \ge 3$
29604
How to solve $\sin x +\cos x = 1$?