Let's take a look at the diagram we have been given.
Examining the diagram, we see that ∠ ABC is a right angle.
m∠ ABC= 90^(∘)
We also see that ∠ ABC equals the sum of ∠ 1 and ∠ 2. Therefore, by the Angle Addition Postulate we can write the following equation.
m∠ 1+ m∠ 2= ∠ ABC
Using the Substitution Property of Equality, we can prove that the sum of m∠ 1 and m∠ 2 equals 90^(∘).
m∠ 1+ m∠ 2= ∠ ABC, m∠ ABC= 90^(∘)
⇕
m∠ 1+ m∠ 2= 90^(∘)
Since the sum of ∠ 1 and ∠ 2 equals 90^(∘), we know that these angles are complementary. Let's show this as a two-column proof.
