Look at the figure shown below.Dora is writing statements as shown to prove that if segment ST is parallel to segment RQ, then x = 12.
1.Segment ST is parallel to segment QR
Given
2.Angle QRT is congruent to angle STP
Corresponding angles formed by parallel lines and their transversal are congruent.
3.Angle SPT is congruent to angle QPR
Reflexive property of angles.
4.Triangle SPT is congruent to triangle QPR
Angle-Angle Similarity Postulate
5.?Corresponding sides of similar triangles are in proportion.