Question

How do the Special Right Triangles relate to the Unit Circle?

Answer 1

Each black-and-red (or black-and-yellow) triangles is a special right-angled triangle. The figures outside the circle - `pi/6, pi/4, pi/3` - are the angles that the triangles make with the horizontal (x) axis. The other figures - `1/2, sqrt(2)/2, sqrt(3)/2` - are the distances along the axes - and the answers to `sin(x)` (yellow) and `cos(x)` (red) for each angle.