Question

If AB and CD are parallel, find the value of x.

Answer 1

AB || CD and BC is the transversal.

$\angle ABC=\angle ECD$ [Alternate angles]

In $\Delta ECD,$
$\angle ECD+\angle CDE+\angle DEC={180}^{\circ }$
[Angle sum property]
${73}^{\circ }+{40}^{\circ }+\text{x}={180}^{\circ }$
$\text{x}={180}^{\circ }-{113}^{\circ }$
$\text{x}={67}^{\circ }$