Can $\sin(xy)$ be written in terms of trigonometric functions of only $x$ or $y$?
7492
Is there a formula for $\sin(xy)$
55436
Why does $A\sin{k(x+c)}=a\sin{kx}+b\cos{kx}$ imply that $A=\sqrt{a^2+b^2}$ and $\tan{c}=-b/a$?
1317
Combining cosine or sine terms into a single cosine or sine
82027
How to derive compositions of trigonometric and inverse trigonometric functions?
100777
Finding the derivatives of sin(x) and cos(x)
31387
Why is $\sin{x} = x -\frac{x^3}{3!} + \frac{x^5}{5!} - \cdots$ for all $x$?
154216
Solve $\sin(z) = z$ in complex numbers
101448
Is $\sin^2(z) + \cos^2(z)=1$ still true for $z \in \Bbb{C}$?
124897
How many ways are there to define sine and cosine?
27513
Trigonometric bounds
108223
If $\cos x=\cos y$ and $\sin x=\sin y$ is $x=y$ or $x=2\pi,y=0$ or $x=0,y=2\pi$? $x,y\in[0,2\pi]$
5080
How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression?
40235
How would I differentiate $\sin{x}^{\cos{x}}?$
125812
Is sin(x) necessarily irrational where x is rational?
103376
Is $\sin(p \pi/q)$ necessarily an algebraic number?
64268
How does a calculator calculate the sine, cosine, tangent using just a number?
87934
Deducing $\sin x + \cos x \ge 1$ from $(\sin x + \cos x)^2 = 1 + 2 \sin x \cos x$