Trig Circle

This interactive circle with a radius of 1 is used in understanding sines, cosines, and tangents of angles found in right triangles. The circle's center is at the origin, and its circumference comprises the set of all points that are exactly one unit from the origin.

To use the unit circle, we put the vertex of an angle at the center of the circle with the first side of the angle extending along the x-axis from the vertex toward the right. The other side of the angle will fall somewhere (depending on the size of the angle) around the circle, counter-clockwise from the first side.

As a point is moved around the circle, the measure of the central angle is displayed in radians and degrees. The coordinates of points around the circle are also displayed in radians for the most important angle measures.

Learning Standards: A2.A.60, A2.A.59, A2.M.2