If A(-5, 7), B(-4, -5), C(-1, -6) and D(4, 5) are the vertices of a quadrilateral

Coordinate Geometry (10)

If A(-5, 7), B(-4, -5), C(-1, -6) and D(4, 5) are the vertices of a quadrilateral, find the area of the quadrilateral ABCD. 

Answer

Area of quad ABCD = Ar ΔABD + Ar ΔBCD

Area of ΔABD =  $\frac{1}{2}$ |(-5)(-5 - 5) + (-4)(5 - 7) + (4)(7 +5)|

= 53 sq units 

Area of ΔBCD = $\frac{1}{2}$ | (-4)(-6-5)+ (-1)(5 +5)+4(-5+6)|

= 19 sq units

Hence, area of quad. ABCD = 53 + 19 = 72 sq units

Exam Year: 2018