High School · Trigonometric Functions

CCSS.MATH.CONTENT.HSF.TF.A.2

Explain how the unit circle in the coordinate plane enables the extension of trigonometric functions to all real numbers, interpreted as radian measures of angles traversed counterclockwise around the unit circle.

Read this standard on the official Common Core site

Lessons that teach this standard

• Solving Trigonometric Equations

  Solve equations like 2 sin x = 1: find one angle, use the unit circle to find every solution in one cycle, and add multiples of the period to get them all.

• The Unit Circle: Sine and Cosine for Every Angle

  Why the right-triangle definition stops at 90°, how the unit circle replaces it, the exact values at π/6, π/4 and π/3, and why sine and cosine repeat.