Recall that the unit circle is the equation x^2 + y^2 = 1 This is a circle with center (h,k) = (0,0) and radius r = 1 It is in the form (x-h)^2 + (y-k)^2 = r^2
We can write the first equation mentioned in the form sin^2(t)+cos^2(t) = 1 Using x = cos(t) y = sin(t) t = angle
The point P(x,y) on the unit circle has an x coordinate of cos(t) and a y coordinate of sin(t). We can see this through drawing a right triangle.
