Question

Find the area of the quadrilateral whose vertices are (-9,-2),(-8,-4),(2,2),(1,-3)

Answer 1

given points

A(-9,-2),B(-8,-4),C(2,2),D(1,-3)

by using formula

=1/2|x1(y2-y3)+x2(y3-y1)+x3(y1-y2)|

divide quadrilateral into 2 triangle

x1,y1 x2,y2. x3,y3

A(-9,-2),B(-8,-4),C(2,2)

=1/2|-9((-4)-(2))+(-8)(2-(-2))+2(-2-(-4))l

=1/2|(-9×-6)+(-8×4)+(2×2)|

=1/2|54-32+4|

=1/2|26|

=13

similarly,∆ADC area is 39/2=19.5

adding both area is 13+19.5=32.5square units

any doubt see above image