Question

In a quadrilateral ABCD, AB || DC and AD || BC. Find the perimeter of triangle COD if the diagonals of the quadrilateral intersect each other at point O and AC = 20in, BD = 20in, AB = 13in.

Answer 1

Draw a diagram as shown below.

The diagonals are equal in length. Because AB || DC and AD || BC, the quadrilateral is a square.

Because the diagonals bisect each other at O, therefore
DO = BO = 10.
Likewise,
AO = CO = 10

Because AB = 13, therefore DC = 13.
The perimeter of ΔCOD is CO + CD + DO = 10 + 13 + 10 = 33 in

Answer: 33 in