The Sine function And Circles

Yesterday we learned that sine is the y coordinate of any point on the unit circle. Thus if we take the circumference of the circle and place it on the x-axis from 0 to 2pi, we can evaluate sin at any point. The result is the graph that represent a stretched out circle.


Graph from wikipedia.

The curve of a circle occurs many places in nature and is used to model frequencies of energy, such as electricity and sound.