$\sin(\alpha \pi/2) = \beta$ where $\alpha,\beta \in \mathbb{Q} \cap [-1,1]$
55302
Rational values of trigonometric functions
46394
If $\frac{\cos \alpha}{\cos \beta}+\frac{\sin \alpha}{\sin \beta}=-1$, find $\frac{\cos^3\beta}{\cos \alpha}+\frac{\sin^3\beta}{\sin \alpha}$.
8919
If $\alpha = \frac{2\pi}{7}$ then the find the value of $\tan\alpha .\tan2\alpha +\tan2\alpha \tan4\alpha +\tan4\alpha \tan\alpha.$
114411
Simple Proof of the Euler Identity $\exp{i\theta}=\cos{\theta}+i\sin{\theta}$
122932
When $(\mathbb{Q}(\zeta_n) : \mathbb{Q}) = 2$?
47356
If : $\tan^2\alpha \tan^2\beta +\tan^2\beta \tan^2\gamma + \tan^2\gamma \tan^2\alpha + 2\tan^2\alpha \tan^2\beta \tan^2\gamma =1\dots$
154216
Solve $\sin(z) = z$ in complex numbers
141273
When is $\sin(x)$ rational?
378
Does $\hat{\beta}=(X′X)^{−1}X′ \ Y$ simplify further?
107067
Finding the argument of $z=1-\cos(2\theta)-i\sin(2\theta)$
104427
Sines and cosines of angles in arithmetic progression
146047
Proving that $\cos(2\pi/n)$ is algebraic
55839
Interior of the Graph of $\sin(1/x)$
124208
Proof $|\sin(x) - x| \le \frac{1}{3.2}|x|^3$
9539
$\alpha$ and $\beta$ are solution of $a \cdot \tan\theta + b \cdot \sec\theta = c$ show $ \tan(\alpha + \beta) = \frac{2ac}{a^2 - c^2}$
64497
prove that $\tan(\alpha+\beta) = 2ac/(a^2-c^2)$
147684
Prove that $\sin \theta=\frac{3 \sin \alpha+\sin^3 \alpha}{1+3\sin^2 \alpha}$ using given condition