Question

• if ∠3 = 65°, what is the measure of its same - side interior angle? • if ∠4 = 120°, find the measure of its alternate interior angle.

Explanation:

Step1: Recall same - side interior angles property

Same - side interior angles are supplementary, i.e., their sum is 180°.
Let the same - side interior angle of ∠3 be x. Then x+65° = 180°.

Step2: Solve for x

x=180° - 65° = 115°.

Step3: Recall alternate interior angles property

Alternate interior angles are congruent. So if ∠4 = 120°, its alternate interior angle has the same measure.

Answer:

The measure of the same - side interior angle of ∠3 is 115°.
The measure of the alternate interior angle of ∠4 is 120°.