Example 2

Use the parallelogram from Example 1 to verify that the opposite angles in a parallelogram are congruent and consecutive angles are supplementary given that and .
  1. Extend the lines in the parallelogram to show two pairs of intersecting lines and label the angles with numbers.
  2. Prove .
  3. Prove .
  4. Prove that consecutive angles of a parallelogram are supplementary.
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