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

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.