Unit Circle Overview

Flashcards covering key concepts of the Unit Circle including degrees, radians, and trigonometric functions.

Unit Circle

A circle with a radius of one, used in trigonometry to define sine, cosine, and tangent values.

0° (0 radians)

Corresponds to the point on the unit circle at (1, 0); sin(0) = 0, cos(0) = 1.

30° (π/6 radians)

Corresponds to the point on the unit circle at (√3/2, 1/2); sin(30°) = 1/2, cos(30°) = √3/2.

45° (π/4 radians)

Corresponds to the point on the unit circle at (√2/2, √2/2); sin(45°) = √2/2, cos(45°) = √2/2.

60° (π/3 radians)

Corresponds to the point on the unit circle at (1/2, √3/2); sin(60°) = √3/2, cos(60°) = 1/2.

90° (π/2 radians)

Corresponds to the point on the unit circle at (0, 1); sin(90°) = 1, cos(90°) = 0.

Tangent (tan)

Defined as the ratio of sine to cosine; tan(θ) = sin(θ)/cos(θ).

Undefined Tangent

Tangent is undefined when cos(θ) = 0, such as at 90° and 270°.