To prove that angles ∠A and ∠R are supplementary in parallelogram GRAM, we can follow these statements and reasons:
Proof Structure:
-
Statement: GRAM is a parallelogram.
Reason: Given. -
Statement: ∠G and ∠A are consecutive interior angles.
Reason: Definition of a parallelogram (opposite sides are parallel, and consecutive interior angles are supplementary). -
Statement: GR || MA.
Reason: Definition of a parallelogram (opposite sides are parallel). -
Statement: ∠A + ∠G = 180°.
Reason: Consecutive Interior Angles Theorem. -
Statement: ∠R and ∠M are consecutive interior angles.
Reason: Definition of a parallelogram. -
Statement: GR || MA.
Reason: Definition of a parallelogram (opposite sides are parallel). -
Statement: ∠R + ∠M = 180°.
Reason: Consecutive Interior Angles Theorem.
Since in parallelograms opposite angles are equal, we have ∠G = ∠M. Thus, substituting that into our earlier statement, we find:
- Statement: ∠A + ∠R = 180°.
Reason: Since ∠G = ∠M, substituting in yields the desired result.
Conclusion:
Thus, ∠A and ∠R are supplementary angles.
This completes the proof that in the parallelogram GRAM, the angles ∠A and ∠R are supplementary.