Cosine and sine functions in time

  As the angle changes we can see what happens to sine and cosine.

They each vary between (and including) positive 1 and negative 1.

Note: we always draw a vertical line to the x-axis to form our triangle.
  Remember, cosine is the x-axis coordinate of the point at the end of the hypotenuse and sine is the y-axis coordinate.

When cosine has a very positive value, the hypotenuse is pointing to the right; a negative value means it is pointing to the left.

When sine has a very positive value, the hypotenuse is pointing up and a negative value means it's pointing down.