Fun fact sin waves are made from a circle radius rotating around where the y of the end of the radius is the y of the sin wave and for a sin wave it starts at 90 degrees and for a cosine wave 0 degrees also, sin and cos waves are mainly used for triginometry like law of the cosines which is ((b^2+c^2-a^2)/(2bc)) or law of the sins which is (a/sin (a))=(b/sin(b))=(c/sin(c)).