Exercise 7 Page 428

Two angles are complementary if the sum of their measures is 90^(∘). Since we are told that ∠1 is a complement of ∠2, we can create an equation to demonstrate this relationship. m∠ 1 + m∠ 2= 90^(∘) We can find m∠ 2 by substituting the given value, m∠1=23^(∘), into the equation.

m∠ 1 + m∠ 2= 90^(∘)

Substitute

m∠ 1= 23^(∘)

23^(∘) + m∠ 2= 90^(∘)

SubEqn

LHS-23^(∘)=RHS-23^(∘)

m∠ 2= 67^(∘)

The measure of ∠ 2 is 67^(∘).