40 points. given: two congruent angles ∠c and ∠r are supplementary. prove: ∠r and ∠c are both right angles. it doesn't have to be exactly 10 rows.statements reasons1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 6. 6. 7. 7. 8. 8. 9. 9. 10. 10.

The proof is explained step-wise below :

Step-by-step explanation:

Given : ∠C and ∠R are supplementary. Also, ∠C and ∠R are congruent

To Prove : ∠C and ∠R are right angles ⇒ ∠C = ∠R = 90°

Proof : Given ∠C and ∠R are congruent and the congruent angles are equal in measure.

⇒ m∠C = m∠R (1)

Now, ∠C and ∠R are supplementary

⇒ ∠C + ∠R = 180°

⇒ ∠C + ∠C = 180°   ( From equation (1) )

⇒ 2∠C = 180°

⇒ ∠C = 90°

Hence, ∠C = ∠R = 90°

⇒ ∠C and ∠R both are right angles.

Hence Proved.