#
The Sine Curve

Blue Length = Blue Length; Red Length = Red Length

The y-coordinate of the point on the unit circle determined by a
central angle (in standard position) of x radians is Sin(x). In a
unit
circle, the radian measure of an angle is the length of the arc
subtended by that angle. To the left of the y-axis, you see a unit
circle being swept out, with the radian measure of the angle (arc
length) shown in blue, and the sine of that angle (the
y-coordinate)
shown in red. To the right of the y-axis, you see the points of
the
graph of y = Sin(x) being graphed in black. The angle x is shown
in
blue and the value of Sin(x) is shown in red.

### Related Sites

The Cosine Curve

The Area of a Circle

The Area of a Circle II

The Pythagorean Theorem

WKU
Mathematics Department .|. WKU
Online

*Last modified, January 29, 2008*

Tom.Richmond@WKU.edu