what is the definition of cosine , sine
124897
How many ways are there to define sine and cosine?
135967
What is the odd Fourier extension of $\sin x \cos(2x)$?
101174
A closed form for a triple integral with sines and cosines
148207
Express $\cos 6\theta $ in terms of $\cos \theta$
43605
If $\sin(a)\sin(b)\sin(c)+\cos(a)\cos(b)=1$ then find the value of $\sin(c)$
100907
$\sin\alpha + \sin\beta + \sin\gamma = 4\cos{\frac{\alpha}{2}}\cos{\frac{\beta}{2}}\cos{\frac{\gamma}{2}}$ when $\alpha + \beta + \gamma = \pi$
50277
Relationship between cosines of angles in 4 dimensions
64255
Trigonometry problem
17188
Simplify $\cos(n \pi)$ and $\sin(n \pi)$ when n is an integer
67035
History of dot product and cosine
81825
Orthogonality of sine and cosine integrals.
94283
Different ways finding the derivative of $\sin$ and $\cos$.
84420
When is $\sin(x) = \cos(x)$?
5080
How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression?
118586
Confused About Trigonometric Substitution
96367
Intuition of Addition Formula for Sine and Cosine
125597
calculator's angle answer for trig ratios that can work in more than 1 quadrant on the unit circle