High School · Trigonometric Functions

CCSS.MATH.CONTENT.HSF.TF.A.3

(+) 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 π-x, π+x, and 2π-x in terms of their values for x, where x is any real number.

Read this standard on the official Common Core site

Lessons that teach this standard

• 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.