High School · Similarity, Right Triangles, and Trigonometry

CCSS.MATH.CONTENT.HSG.SRT.C.6

Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.

Read this standard on the official Common Core site

Lessons that teach this standard

• Special Right Triangles: 45-45-90 and 30-60-90

  Where the side ratios of the two special right triangles come from, how to use them without a calculator, and the exact sine, cosine and tangent values they give.

• Trigonometric Ratios: Sine, Cosine and Tangent

  Why a side ratio in a right triangle depends only on the angle, what SOH CAH TOA names, why sine equals the cosine of the complement, and how to find a missing side.