Why is $\cos(i)-i \sin(i)=e$?
66227
Why Euler's formula is true?
40837
Why $e^{i(π/3)} \ne -1$?
24929
Why did Euler use e to represent complex numbers?
77517
Why is this sum a representation of e?
100968
Why is $|e^{i \lambda z}| |e^{- \lambda y}|= |e^{- \lambda y}|$ here?
31552
A contradictory integral: $\int \sin x \cos x \, \mathrm dx$
60793
Why is $\sin(d\Phi) = d\Phi$ where $d\Phi$ is very small?
66872
Exact values of $\cos(2\pi/7)$ and $\sin(2\pi/7)$
96328
Proving $e^{i\pi} = -1$ without proving $e^{ix} = \cos x + i\sin x$
23397
Why it's true? $\arcsin(x) +\arccos(x) = \frac{\pi}{2}$
83359
Complex number identity by trigonometry
38949
How to Evaluate $\int e^{2x}\sin(3x)\ dx$?
17188
Simplify $\cos(n \pi)$ and $\sin(n \pi)$ when n is an integer
29370
Trig integral $\int ( \cos{x} + \sin{x}\cos{x}) \, dx $
108223
If $\cos x=\cos y$ and $\sin x=\sin y$ is $x=y$ or $x=2\pi,y=0$ or $x=0,y=2\pi$? $x,y\in[0,2\pi]$
141540
What is wrong with the following "proof" that $e=1$?
5747
$\cos(\arcsin(x)) = \sqrt{1 - x^2}$. How?