Deriving the sin and cos addition formulas using Euler's formula
40556
Why is $\sin(\alpha+\beta)=\sin\alpha\cos\beta+\sin\beta\cos\alpha$
7003
Inductive proof of a formula for Fibonacci numbers
100777
Finding the derivatives of sin(x) and cos(x)
10289
Need help in proving that $\frac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} = \frac 1{\sec\theta - \tan\theta}$
23238
Linear combinations of sine and cosine
17690
Ways to prove Euler's formula for $\zeta(2n)$
74143
Simplifying and evaluating $\cot 70^\circ+4\cos 70^\circ$
93212
Express $\sqrt{3}\sin\theta - \cos\theta$ as: $a\cos (\theta + \alpha) $
1210
Write an expression for $(\cos θ + i\sin θ)^4$ using De Moivre’s Theorem.
34590
Fourier series of Log sine and Log cos
137376
Proving a trig identity: $\frac{\sin(A + B)}{\sin(A - B)}=\frac{\tan A + \tan B}{\tan A - \tan B}$
86454
How to prove $\cos\left(\pi\over7\right)-\cos\left({2\pi}\over7\right)+\cos\left({3\pi}\over7\right)=\cos\left({\pi}\over3 \right)$
60275
calculation of $\int\frac{1}{\sin^3 x+\cos^3 x}dx$ and $\int\frac{1}{\sin^5 x+\cos^5x}dx$
69478
Deducing a $\cos (kx)$ summation from the $e^{ikx}$ summation
108245
Solving the complex equation $\sin(z) = \cos(z)$
31575
Solving trigonometric equations of the form $a\sin x + b\cos x = c$
122169
Prove $\sin(\pi/2)=1$ using Taylor series