### Home > PC > Chapter 4 > Lesson 4.2.1 > Problem4-72

4-72.

Use the Fundamental Pythagorean Identity to simplify each trig expression.

1. $\text{cos}^2 θ +\text{sin}^2 θ$

1. $1 − \text{cos}^2 θ$

1. $1 − \text{cos}^2 5$

1. $1 −\text{ sin}^2 β$

1. $1 −\text{ sin}^2 (3δ)$

$\text{cos}^2(3δ)$

1. $4 − 4\text{ sin}^2 (3δ)$

Factor out a $4$ first.