The process of expanding using double-angle formulas involves representing a trigonometric function of a double angle in terms of singular angles. The formulas that are used in this process include sin2A = 2sinAcosA, cos2A = cos²A - sin²A, or alternatively, 2cos²A - 1, or 1 - 2sin²A. These formulas are critical in simplifying expressions and resolving trigonometric equations.
| Topic | Problem | Solution |
|---|---|---|
| None |
Expand |
First, recall the double-angle formula for cosine: |