# Thread: Area of a triangle

1. ## Area of a triangle

For question 4, given that the rectangle ABCD is folded along the diagonal BD, where AB = 4 and BC = 6, determine the area of BPD

I struggled for half an hour figuring out why the poorly written solution is the solution, but for the life of me couldn't get the last step. Why is the area 1/2 BP x CD???

2. It took me a while to figure it out, but we know that

BP = PD (deduced in the problem)
AB = CD = 4
because we were given a rectangle ABCD originally, and then we folded it.

S = (1/2) BP * CD = (1/2) PD * AB = 26/3

Now its easier to see PD is the base and AB is the height.

EDIT: your h in the diagram would have to correspond to the base BD