Q. If the area of the triangle with vertices $(x, 0)(1,1)\, \&\,(0,2)$ is $4$ square units. Then the value of $x$ is.

Solution:

Area $=\frac{1}{2}\begin{vmatrix}x & 0 & 1 \\ 1 & 1 & 1 \\ 0 & 2 & 1\end{vmatrix}$
$4 =\frac{1}{2}[x(1-2)-0+1(2-0)]$
$8 =-x+2,$
$\therefore x =2-8, x =-6$