Question

Question 4(iii)
Find the value of x in each of the following figures if l || m

Answer 1

(Given, $a\parallel b$ and $l\parallel m$

Mark an angle 1 in the figure.

$\angle 1={80}^{\circ }$ [Since 'a' is parallel to 'b', they are corresponding angles]

Now,

$\angle 1+\angle x={180}^{\circ }$ [Since $l\parallel m,\angle 1and\angle x$ are cointerior angles]

$\Rightarrow \angle x={180}^{\circ }-{80}^{\circ }$

$\Rightarrow \angle x={100}^{\circ }$