In Fig., ABCDE is any pentagon. BP drawn parallel to AC meets DC produced at P and EQ drawn parallel to AD meets CD produced at Q. Prove that ar (ABCDE) = ar (APQ)
Solution.
Given: a pentagon ABCDE, and
To prove:
Proof: We know that triangles on the same base and between the same parallel lines are equal in area.
Now, and lie on the same base AD and lie between the same parallels AD and EQ. So,
…(i)
Similarly,
and lie on the same base AC and lie between the same parallels AC and PB
…(ii)
On adding equations (i) and (ii), we get
Adding ar (DCDA) to both sides, we get
Hence proved.