Prove that consecutive angles of the parallelogram are supplementary
Answers
Step-by-step explanation:
Prove: *If a quadrilateral is aparallelogram, then the consecutive angles are supplementary. Prove:Angle BAD and angle CBA aresupplementary. *This is a proof for a single pair of consecutive angles. To fully prove the statement above, the 3 other pairs of consecutive anglesmust also be proved to besupplementary.
Answer:
AB ∥ CD and AD is a transversal.
We know that interior angles on the same side of a transversal are supplementary.
Therefore, ∠A + ∠D = 180°
Similarly, ∠B + ∠C = 180°, ∠C + ∠D = 180° and ∠A + ∠B = 180°.
Therefore, the sum of any two adjacent angles of a parallelogram is equal to 180°.
Hence, it is proved that any two adjacent or consecutive angles of a parallelogram are supplementary.
If one angle is a right angle, then all four angles are right angles:
From the above theorem, it can be decided that if one angle of a parallelogram is a right angle (that is equal to 90 degrees), then all four angles are right angles. Hence, it will become a rectangle.
Since, the adjacent sides are supplementary.
For example, ∠A, ∠B are adjacent angles and ∠A = 90°, then:
∠A + ∠B = 180°
90° + ∠B = 180°
∠B = 180° – 90°
∠B = 90°
Similarly, ∠C = ∠D = 90°