Question

In the given figure, m and n are two mirrors placed parallel to each other. An incident ray AB strikes the mirror m at point B and then reflected to the mirror n along path BC and again reflects back along CD. Prove that AB || CD.

Answer 1

Given: Two plane mirrors m and n are in such a way that m || n. In incident ray AB after reflection, reflects along BC and CD. BM and CN are normal respectively on mirror m and n. 

To prove: AB || CD 

Proof: ∵ BM ⊥ m, CN ⊥ n. and m||n 

CN ⊥ m => BM || CN

For two parallel lines BM and CN a transversal line BC intersects at points B and C.