Question 12 Marks
$\text{ABCD}$ is a parallelogram. The bisector of $\angle BAD$ meets $\text{DC}$ at $P,$ and $\text{AD}$ is half of $\text{AB}.$

Prove that$: \text{BP}$ bisects $\angle ABC.$

Prove that$: \text{BP}$ bisects $\angle ABC.$
Answer
View full question & answer→Since $\text{PC} =\text {BC} ...(\text{AD}$ is half of $\text{AB}$ and $\text{BC} =\text {AD}$ and $\text{DC} = \text{AB})$
$∠CPB = ∠CBP$
But $∠CPB = ∠PBA ...($alternate angles $∵\text{DC} \| \text{AB})$
$⇒ ∠CBP = ∠PBA$
Therefore, $\text{BP}$ bisects $∠ABC.$
$∠CPB = ∠CBP$
But $∠CPB = ∠PBA ...($alternate angles $∵\text{DC} \| \text{AB})$
$⇒ ∠CBP = ∠PBA$
Therefore, $\text{BP}$ bisects $∠ABC.$
