The trig functions are made from the unit circle..................b/c its radius is one..............therefore the math is easier..............................a number divided by one........is the number..............

A circle whose radius is 1/2...............would have a diameter of 1...........so the circumference would be pi exactly.......The red circle below............pi is a relationship.......also an irrational #.............a circle's circumference divided by its diameter........................could u make a circle of diameter..............1/2 and unfold it.........like a string.........to make pi exactly??