We show the sine in the unit circle. The unit circle is a circle with radius equation.

sin-circle

The hypotenuse of the triangle in the unit circle has a length of 1. In this case sine is equal to the opposite:

    equation

The sine function is the length of the opposite with regards to the angle equation. One can easily observe that:

(1)   equation

This is the plot of the sine function between 0 and equation:

sin

Here are some values of the sine functions that are worth remembering:

Alpha in degree Alpha in radians Value of sine of alpha
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