Question

In the figure, if $EC\left|\right|AB,\angle ECD={70}^{\circ }$and$\angle BDO={20}^{\circ },then\angle OBD$ is

Answer 1

In the figure ,$EC\left|\right|AB,\angle ECD={70}^{\circ },\angle BDO={20}^{\circ }$

$\because EC\left|\right|AB$

$\angle AOD=\angle ECD$ (Corresponding angles)

$\Rightarrow \angle AOD={70}^{\circ }$

In $\Delta OBD,$

Ext. $\angle AOD=\angle OBD+\angle BDO$

${70}^{\circ }=\angle OBD+{20}^{\circ }$

$\Rightarrow \angle OBD={70}^{\circ }-{20}^{\circ }={50}^{\circ }$