Aconjecture and the flowchart proof used to prove the conjecture are shown.

given: a b c d is a parallelogram. prove: angle 1 is supplementary to angle 3. art: parallelogram a b c d. ray d b is drawn and is extended past vertex b. the ray forms an interior angles a d b and d b c and an exterior angle labeled as 3, adjacent to angle d b c. angle a d b is labeled as 1, and angle d b c is labeled as 2.

drag an expression or phrase to each box to complete the proof.