Answer:
Given,
p and r are parallel lines,
We have to prove that : ∠1 is supplementary to ∠7.
Thus, the column prove would be,
Statement Reason
1. Line p is parallel to line r. 1. Given
2. ∠2≅∠7 2. Exterior alternate angle theorem,
3. m∠2=m∠7 3. Property of congruence,
4. ∠1 and ∠2 form a linear pair. 4. Adjacent angle on straight line,
5. ∠1 is supplementary to ∠2 5. Linear pair postulate
6. m∠1+m∠2=180° 6. Supplementary angle property
7. m∠1+m∠7=180° 7. Substitution property
8. ∠1 is supplementary to ∠7 8. Supplementary angle property
