Question

Find the area of $△PQR$ whose vertices are $P(2,1),Q(3,4)$ and $R(5,2)$.

Answer 1

Area of $\Delta =\frac{1}{2}\left|\begin{array}{ccc}1& 1& 1\\ 2& 3& 5\\ 1& 4& 2\end{array}\right|$

$=\frac{1}{2}\left[\right(6-10)+(5-4)+(8-3\left)\right]$

$=\frac{1}{2}[-4+1+5]=1$ sq.units.