# The y axis for the sine wave

by PhotonW/mass
Tags: axis, sine, wave
 P: 11 Okay this has been bothering me, I know what the x axis on sine graph mean, but not the y axis. I know when I type for example: sin(pi) I will get 1. But what is that 1? I know its the y cordnate. But what is it?
 Emeritus Sci Advisor HW Helper Thanks PF Gold P: 6,517 It's the amplitude of the sine wave. Since the sine function is related to a unit circle, think of the amplitude as the y coordinate on the unit circle when the radius makes an angle theta to the positive x-axis.
 P: 22 Sine(pi) equals zero. Geometrically the sine of angle α equals the length of the opposite side divided by the length of the hypotenuse in a right triangle. The particular size of the triangle is unrelevant as long as it contains the angle. In an unit circle centered at the origin sine(α) equals the distance of a point on the circumference (at angle α) from the x-axis. It corresponds to the imaginary part of e^(iα) in complex analysis.
Math
Emeritus