Question

Given lines $l_1,l_2$ and $l_3$ in fig. 2 are parallel. The value of $x$ is :

• A. ${40}^{\circ }$
• B. ${140}^{\circ }$
• C. ${50}^{\circ }$
• D. ${60}^{\circ }$

Answer 1

The correct option is B ${140}^{\circ }$

$l_1||l_3$ and $l_4$ is transversal line.

$\therefore \angle 1={40}^{\circ }$ (Corresponding angles)

Now $\angle x+\angle 1={180}^{\circ }$ (Angles made on the same line )

$\Rightarrow \angle x+{40}^{\circ }={180}^{\circ }\Rightarrow \angle x={180}^{\circ }-{40}^{\circ }\Rightarrow \angle x={140}^{\circ }$