Sections 2.5 Multiple-Angle and Product-to-Sum Formulas

Section Objectives

  1. Use double-angle formulas to rewrite trigonometric expressions.
  2. Use power-reducing formulas to rewrite trigonometric expressions.
  3. Use product-to-sum and sum-to-product formulas to rewrite trigonometric equations.



Double-angle Formulas

The double-angle formulas follow immediately from the sum formulas.



Examples










Power-reducing and Half-angle Formulas

These formulas are easily derived from the double-angle formulas.



Examples







Product-to-sum formulas

These formulas are easy to derive from the sum and difference formulas.



Examples