Question
In the given figure, $AB || CD$. Prove that $\angle\text{BAE}-\angle\text{ECD}=\angle\text{AEC}.$

Answer


Draw $\text{EF}||\text{AB}||\text{CD}$ through $E$.
Now, $\text{EF}||\text{AB}$ and $AE$ is the transversal.
Then, $\angle\text{BAE}+\angle\text{AEF}=180^\circ$ [Angles on the same side of a transversal line are supplementary]
Again, $\text{EF}||\text{CD}$ and $CE$ is the transversal.Then,
$\angle\text{DCE}+\angle\text{CEF}=180^\circ$ [Angles on the same side of a transversal line are supplementary]
$\Rightarrow\angle\text{DCE}+(\angle\text{AEC}+\angle\text{AEF})=180^\circ$
$\Rightarrow\angle\text{DCE}+\angle\text{AEC}+180^\circ-\angle\text{BAE}=180^\circ$
 $\Rightarrow\angle\text{BAE}-\angle\text{DCE}=\angle\text{AEC}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free