Chapter 1.6, Problem 7PSB

To determine

To Prove: $\text{If }\angle 1\cong \angle 2\text{ both are right angles}\text{.}$

Explanation of Solution

Given:

  

Concept Used:

Sum of linear pairs of angles is $180°$ .

Proof:

Here, we have

  $\begin{array}{l}\angle 1\text{and }\angle 2\text{are linear pair of angles}\text{.}\\ \Rightarrow \angle 1+\angle 2=180°\\ \Rightarrow 2\times \angle 1=180°\\ \Rightarrow \angle 1=90°=\angle 2\\ \Rightarrow \angle 1\text{and }\angle 2\text{are right angles}\text{.}\end{array}$