A conjecture 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.

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