Question

in fig.6.90 pq and qr are two plane mirrors placed perpendicular to each other. an incident ray ab strikes the mirror pq at b and reflected towards bc. the reflected ray bc strikes the mirror qr at c and reflected towards cd. prove that ab||cd from RS Agarwal​

Answer 1

Answer:

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Step-by-step explanation:

From laws of refection ∠1=∠2and∠3=∠4 (IMAGE)

So, ∠1=∠2=

2

1

∠ABCand∠3=∠4=

2

1

∠BCD

Here BM and CN are Normal

So BM⊥PQandCN⊥RS

put,PQ∥RS

So, BM∥CN

Now BM∥CN, and BC is transversal

⇒∠2=∠3

⇒

2

1

∠ABC=

2

1

∠DCB

⇒∠ABC=∠BCD

AB∥CD as it transversal BC

Intersect two lines such that pair of interior angle is equal then lines are parallel.