Expii

# Unit Circle in Trigonometry - Expii

For every angle x we get a point on the unit circle, (cos x, sin x), by rotating from (1, 0) by an angle of x. Don't worry, the cos and sin here are the same as the familiar right triangle cosine and sine when x is an acute angle. The advantage is that cos(x) and sin(x) are now defined for all reals x, which is useful in applications of trig.