how to find this trigonometric sum?
83332
Trig sum: $\tan ^21^\circ+\tan ^22^\circ+\cdots+\tan^2 89^\circ = \text{?}$
35244
Prove $\sin^2\theta + \cos^2\theta = 1$
43903
Find the sum for $\sum_{n=1}^{\infty}(-1)^{(n+1)}\frac{2n+1}{3^n} $
89319
How can I find all the solutions of $\sin^5x+\cos^3x=1$
42424
Riemann sum of $\sin(x)$
154172
Finding $\tan t$ if $t=\sum\tan^{-1}(1/2t^2)$
155611
Sum of series $\frac{1}{2 \cdot 3 \cdot 4} + \frac{1}{4 \cdot 5 \cdot 6} + \frac{1}{6 \cdot 7 \cdot 8} + \cdots $
141978
How to find the infinite sum
112950
Find the value of infinite series $\sum_{n=1}^{\infty} \tan^{-1}(2/n^2)$
18814
Sum of the series $1+\frac{1\cdot 3}{6}+\frac{1\cdot3\cdot5}{6\cdot8}+\cdots$
9479
$\sum \cos$ when angles are in arithmetic progression
152169
How would we solve this trigonometric equation using vectors?
108010
Evaluating $\sum_{k=1}^{\infty}\left(\frac{\sin(tk)}{k}\right)^2$
141645
Trigonometric series sum proof
43605
If $\sin(a)\sin(b)\sin(c)+\cos(a)\cos(b)=1$ then find the value of $\sin(c)$
95979
Trigonometry and algebra question
143753
Please help me to find the sum $\sum\limits_{n\geq1} \frac{\sin(nx)}{n^2}$