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.

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.

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

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

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.

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

In this topic, we will learn what an angle is and how to label, measure and construct them. We will also explore special types of angles.

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.