Question

find the area of tri PQR whose vertices are P(-5,7),Q(-4 ,-5) and R(4,5)

Answer 1

A=1/2[x1(y2-y3)+x2(y3-y1)+x3(y1-y2)]
=1/2[-5(-10)-4(-2)+4(12)]
=1/2(50+8+48)
=1/2(106)
=53 square units

Answer 2

The area of the triangle with vertices (-5, 7), (-4, -5) and (4, 5) is 53 sq.units

Given vertices

              P = (-5, 7) = $(x_{1}, y_{1})$

             Q = (-4, -5) = $(x_{2}, y_{2})$

              R = (4, 5) = $(x_{3}, y_{3})$

Area of triangle PQR is calculated as follows