Learn how to use the unit circle to define sine, cosine, and tangent for all real numbers.

For each point on the unit circle, select the angle that corresponds to it. Click each dot on the image to select an answer.

For each point on the unit circle, select the angle that corresponds to it. Click each dot on the image to select an answer.

For each point on the unit circle, select the angle that corresponds to it. Click each dot on the image to select an answer.

Learn the relationship between the radius, diameter, and circumference of a circle.

When you add or subtract any multiple of π to an angle, it results in an angle that is in the same position on the unit circle, and the tangent function has the same value at that angle.

Sal finds trigonometric identities for sine and cosine by considering angle rotations on the unit circle.

About this unit Explore, prove, and apply important properties of circles that have to do with things like arc length, radians, inscribed angles, and tangents.

With the unit circle and the Pythagorean theorem, we can find the exact sine, cosine, and tangent of the angles π/6 and π/3.

You can use the circumference to get the radius of the circle, and then get area from there. In other words, radius bridges the gap between circumference and area.