Question

Find the area of $△PQR$ whose vertices are $P(-1,1)Q(0,5)R(3,2)$

Answer 1

$Area=\frac{1}{2}\left[x_1\right(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2\left)\right]$

By substituting the values we get,

$=\frac{1}{2}[-1(5-2)+0(2-1)+3(1-5\left)\right]$

$=\frac{1}{2}[-1(3)+0+3(-4\left)\right]$

$=7.5$ sq units