Explain sine and cosine relationship

What you'll learn

1. Define complementary angles and identify complementary angle pairs in right triangles
2. Explain why the sine of one acute angle equals the cosine of its complement
3. Prove the complementary angle relationship using right triangle geometry
4. Apply the relationship sin(θ) = cos(90° - θ) to solve problems
5. Use the complementary relationship to find trig values without a calculator
6. Understand how this relationship simplifies trigonometric calculations

Prerequisites

• Understand trigonometric ratios