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Special Triangles & Unit Circle


Videos and lessons to help High School students learn how to use special triangles to determine geometrically the values of sine, cosine, tangent for π/3, π/4 and π/6, and use the unit circle to express the values of sine, cosine, and tangent for x, π + x, and 2π – x in terms of their values for x, where x is any real number.

Common Core: HSF-TF.A.3

Related Topics:
Common Core (Functions)

Common Core for Mathematics

Introduction to Trigonometric Functions Using Triangles
Defines trigonometric functions using right triangles.

Sine, Cosine, & Tangent of π/3, π/4, π/6
This video demonstrates geometrically the values of Sine, Cosine, and Tangent for angles with radian measures π/3, π/4, π/6.

Trig Values of Special Angles F.TF.3
Find the trigonometric function values at critical angles between 0 and π/2, and use the unit circle to find trigonometric values at intervals of π (tangent) or 2π (sine and cosine) beyond them.

Deriving Values on the Unit Circle
Derive the values in the first quadrant of the unit circle using geometry and the pythagorean theorem.


A way to remember the Entire Unit Circle for Trigonometry.

Unit Circle
Unit Circle

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