### Home > PC > Chapter 4 > Lesson 4.1.1 > Problem4-8

4-8.

Given the equation $s^2 + c^2 = 1$, simplify each of the following expressions.

Rewrite the given equation in its various forms.
Substitute the appropriate expressions in the problems below.

$s^2 = 1 − c^2$
$c^2 = 1 − s^2$

1. $c^2 + s^2$

This is the same as: $s^2 + c^2$

1. $1 − c^2$

1. $1 − s^2$

1. $s + c$

This cannot be further simplified.

1. $4(1 - s^2)$

1. $4 − 4s^2$

Factor out a $4$ first. Then substitute an expression for $s^2$.