Find formula of sum $\sin (nx)$
5080
How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression?
44577
Finding a formula to sum natural numbers up to $n$
85944
Prove $ \sin x + \frac{ \sin3x }{3} + ... + \frac{ \sin((2n-1)x) }{2n-1} >0 $
146746
A formula for the sum of the triangular numbers?
147886
Proof of the angle sum identity for $\sin$
16253
Proof that $|\sin(nx)| \le n|\sin(x)|$
116360
Sum of n-th roots of unity
125087
Evaluate the limit of ratio of sums of sines (without L'Hopital): $\lim_{x\to0} \frac{\sin x+\sin3x+\sin5x}{\sin2x+\sin4x+\sin6x}$
42424
Riemann sum of $\sin(x)$
32823
Prove $\forall n \in \mathbb{N}: \int_{0}^{\frac{\pi}{2}} |\frac{\sin(nx)}{x}|dx \geq \frac{2}{\pi}\sum_{k=1}^{n}\frac{1}{k}$
137844
Proof of $\sin nx=2^{n-1}\prod_{k=0}^{n-1} \sin\left( x + \frac{k\pi}{n} \right)$
47572
Evaluate $ \sum_{n=1}^{\infty} \frac{\sin \ n}{ n } $ using the fourier series
141645
Trigonometric series sum proof
136066
Find the sum $\sum _{n=1}^{\infty }\left(\sqrt{n+2}-2\sqrt{n+1}+\sqrt{n}\right)$
39659
Is there a closed formula for this summation?
57330
Find the number of solutions of $\sin x+2 \sin 2x- \sin 3x=3$
74120
Find the value of $\sum_{n=1}^{\infty} \frac{2}{n}-\frac{4}{2n+1}$