High School · Similarity, Right Triangles, and Trigonometry

CCSS.MATH.CONTENT.HSG.SRT.D.11

(+) Understand and apply the Law of Sines and the Law of Cosines to find unknown measurements in right and non-right triangles (e.g., surveying problems, resultant forces).

Read this standard on the official Common Core site

Lessons that teach this standard

• The Law of Cosines

  Why c² = a² + b² − 2ab cos C is the Pythagorean theorem with a correction, proved with coordinates, and how to find a side from SAS or an angle from SSS.

• The Law of Sines, and the Ambiguous Case

  Why each side of a triangle over the sine of its opposite angle gives the same number, how to solve triangles with it, and why SSA can give two triangles or none.