Find the measure of the longer diagonal

Question

A parallelogram has sides of length 20 units and 10 units. The shorter diagonal is 12 units. Find the measure of the longer diagonal.

Answer 1

12² + x² = 2(20² + 10²); x² = 1000 - 144; x² = 856; x = √856 = 2√21Property of parallelogram:

Sum of squares of parallelogram equal sum of squares all sides.