Question

The vertices of a parallelogram are at (-9, 12), (-3, 12), (-5, 10), and (–11, 10). What is the perimeter of the parallelogram? Round your answer to the nearest whole number?

Answer 1

let point A has coordinates (-9;12),B(-3;12),C(-5;10) and D(-11;10).Then the vector AB={6;0}, BC={2;-2}, CD={6;0}, AD={2;-2} and their and the length of the vectors

$|AB| = |CD| = \sqrt{ {6}^{2} + {0}^{2} } = \sqrt{36} = 6 \\ |BC| = |AD| = \sqrt{ {2}^{2} + {( - 2)}^{2} } = \sqrt{8}$

$p = 6 + 6 + \sqrt{8} + \sqrt{8} = \\ = 12 + 2 \sqrt{8} = 17.66\approx18$