Find the area of the triangle whose vertices are $(3, 8), (-4, 2)$ and $(5, 1)$.

$30.5$ sq. units

The correct answer is Option (2) → $30.5$ sq. units ##

The area of triangle is given by

$\Delta = \frac{1}{2} \begin{vmatrix} 3 & 8 & 1 \\ -4 & 2 & 1 \\ 5 & 1 & 1 \end{vmatrix}$

$= \frac{1}{2} [3(2 - 1) - 8(-4 - 5) + 1(-4 - 10)]$

$= \frac{1}{2} (3 + 72 - 14) = \frac{61}{2}$