Question

In the given figure, if l₁ || l₂, what is the value of y?



(a) 100

(b) 120

(c) 135

(d) 150

Answer 1

Given figure is as follows:

It is given that .

and 3x are vertically opposite angles, which must be equal, that is,

(i)

Also, and x are consecutive interior angles.

Theorem states: If a transversal intersects two parallel lines, then each pair of consecutive interior angles are supplementary.

Thus,

From equation (i), we get:

x and y form a linear pair. Therefore, their sum must be supplementary.

Thus,

Substituting, in equation above, we get:

Hence, the correct choice is (c).