If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

To log in and use all the features of Khan Academy, please enable JavaScript in your browser.

The unit circle definition of sine, cosine, and tangent

Introduction to radians

Learn

Intro to radians

(Opens a modal)

Radians & degrees

(Opens a modal)

Degrees to radians

(Opens a modal)

Radians to degrees

(Opens a modal)

Radian angles & quadrants

(Opens a modal)

Practice

Radians & degreesGet 3 of 4 questions to level up!

The unit circle definition of sine, cosine, and tangent

Learn

(Opens a modal)

The trig functions & right triangle trig ratios

(Opens a modal)

Trig unit circle review

(Opens a modal)

The graphs of sine, cosine, and tangent

Learn

Graph of y=sin(x)

(Opens a modal)

Graph of y=tan(x)

(Opens a modal)

Intersection points of y=sin(x) and y=cos(x)

(Opens a modal)

Basic trigonometric identities

Learn

Sine & cosine identities: symmetry

(Opens a modal)

Tangent identities: symmetry

(Opens a modal)

Sine & cosine identities: periodicity

(Opens a modal)

Tangent identities: periodicity

(Opens a modal)

Trigonometric values of special angles

Learn

Trig values of special angles

(Opens a modal)

Practice

Trig values of special anglesGet 3 of 4 questions to level up!

The Pythagorean identity

Learn

Proof of the Pythagorean trig identity

(Opens a modal)

Using the Pythagorean trig identity

(Opens a modal)

Pythagorean identity review

(Opens a modal)

Practice

Use the Pythagorean identityGet 3 of 4 questions to level up!

Long live Tau

Learn

(Opens a modal)

Pi is (still) wrong

(Opens a modal)

About this unit

Learn how the trigonometric ratios are extended to all real numbers using algebra. Start solving simple problems that involve this new definition of the trigonometric functions.