In the given figure, PQ and RS are two mirrors placed parallel to each other. An incident ray AB strikes the mirror PQ at B, the reflected ray moves along the path BC and strikes the mirror RS at C and again reflects back along CD. Prove that AB || CD.
In the given figure, if PQ || ST, ∠PQR = 110º and ∠RST = 130º, find ∠QRS.
[Hint: Draw a line parallel to ST through point R.]