Illustrative Mathematics
Illustrative Mathematics: F Tf Trigonometric Ratios and the Pythagorean Theorem
The purpose of this task is to use the Pythagorean Theorem to establish a fundamental trigonometric identity for an acute angle. The reasoning behind this identity is then applied to calculate a cosine for a given obtuse angle. Aligns...
Illustrative Mathematics
Illustrative Mathematics: F Tf Calculations With Sine and Cosine
The goal of this task is to study some values of sin x and cos x for different angles, and to look for and then explain patterns that are seen. Aligns with HSF-TF.C.8.
Khan Academy
Khan Academy: Algebra Ii: Use the Pythagorean Identity
Given the sine (or cosine) of an angle, find its cosine (or sine) using the Pythagorean identity. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.