Why in calculus the angles are measured in radians?
39862
Why does the derivative of sine only work for radians?
147334
We have angle=arctan(dy/dx), but what happens when dx=0?
82586
Why is cos -x equal to cos x?
126701
How to prove that $d \sin(x)/dx = \cos(x)$ without circular logic such as L'Hôpital's rule?
40556
Why is $\sin(\alpha+\beta)=\sin\alpha\cos\beta+\sin\beta\cos\alpha$
113516
Why can we only add or subtract things of the same dimension (meters/second, newtons, etc)?
50277
Relationship between cosines of angles in 4 dimensions
53661
Intuition surrounding units in $R[x]$
106483
How to find angle x without calculator?
84420
When is $\sin(x) = \cos(x)$?
5747
$\cos(\arcsin(x)) = \sqrt{1 - x^2}$. How?
43637
Derivative of the sine function when the argument is measured in degrees
69250
Where does the formula for the moment of inertia $I = \int r^2 dm$ come from?
25913
Is writing $dx^2$ same as writing $d(x^2)$ in calculus
41340
Why do clocks measure arc-length?
18005
Angle notation for complex numbers in polar form
143584
Trigonometric ratios for angles greater than $90^\circ$?