Chapter 3.5, Problem 11PPS

To determine

To state the postulate or theorem justify the answer.

  $m\angle 7+m\angle 8={180}^{°}$

Answer to Problem 11PPS

Theorem of co-interior angles is used.

Explanation of Solution

Given information:

Figure

  $m\angle 7+m\angle 8={180}^{°}$

Figure

Co-interior angles

When two parallel lines are cut by a transversal and sum of interior angle is ${180}^{°}$ .

In figure $\angle 7$ is on the line r and transversal v and $\angle 8$ is on the line s and transversal v are

Co-interior angles.

In figure parallel lines are

  $r\left|\right|s$

Then

  $m\angle 7+m\angle 8={180}^{°}$

Hence, $m\angle 7+m\angle 8={180}^{°}$ are co-interior angles.