NCERT Class 9 Solutions: Line and Angles (Chapter 6) Exercise 6.2 – Part 3
Q5 In the figure, if and find x and y.
Solution:
Given,
and
Now,

(Alternate interior angles.)

(Angles on the same side of transversal.)


Thus,

(AB is a straight line.)



Q6 In the 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. Prover that .
Solution:
Construction: Draw
Since, and . Thus,

………..equation(1) (Alternate interiror Angle)

………….equation(2) (Angle of incidence=Angle of reflection

…………..equation (3) (Angle of incidence=Angle of reflection)
From (1),(2) and (3),we get ………..equation(4)
Adding (1)and(4),we get
But these are alternate interior angle and they are equal.
Therefore, .