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 \(\cos^2x\) using double-angle formulas. | First, recall the double-angle formula for cosine: \(\cos2x = 1 - 2\sin^2x\) or \(\cos2x = 2\cos^2x… |