PreCalc · Unit 9

Double-Angle Formulas

sin(2a), cos(2a)

Curriculum standard — Represent stage of the Thinking Ladder

Multiple representations

The symbolic form of this concept.

Three pathways, one topic

Study double-angle formulas at three depths

Grade/course-level problems with full understanding.

Parameters, multiple representations, proof, and modeling.

Non-routine problems and competition applications.