Given the figure with ∠CDE ≅ ∠A and L ⊥ line AB. Prove that L ⊥ line DE. Kindly use Two-column proof.

Question

Answer 1

The title of the question refers to angle CDE. The point between A and C that's labeled B is mis-labeled, it should be labeled D.

The angle CDE is congruent to the angle CAB. Therefore lines DE and AB are parallel.

Line L is perpendicular to line AB. Because lines DE and AB are parallel, line L is also perpendicular to line DE.