The equation for the unit circle...................is below.........for the r = 1/2 circle............is the same..........but the number on the right........is 1/4.................like 14i...........1/4 = 0.25.........so many 25s...............and 2 's and 5's..........half of the primes in single digits............2, 3, 5, 7..........1/2 of them............is in 1/4th........1/4 = 0.25.......................2 and 5................is 1/2 of all primes in single digits.................................................multiplying beg to end and the two middle numbers........2 * 7 = 14.............like 14i..............3 * 5 = 15............................like 15i.........like 14.13i is between 14 i and 15 I....................

PythagorasPythagoras' Theorem says that for a right angled triangle, the square of the long side equals the sum of the squares of the other two sides:

x² + y² = 1²

But 1² is just 1, so:

x² + y² = 1
(the equation of the unit circle)

Also, since x=cos and y=sin, we get:

(cos(θ))² + (sin(θ))² = 1

a useful "identity"