Question

The area of triangle with vertices $(K,0),(4,0),(0,2)$ is $4$ square units, then the value of $K$ is

• A. $0$ or $8$
• B. $0$ or $-8$
• C. $0$
• D. $8$

Answer 1

The correct option is A $0$ or $8$

$\text{Area}$ =$\frac{1}{2}\left|\begin{array}{ccc}1& K& 0\\ 1& 4& 0\\ 1& 0& 2\end{array}\right|$
$\Rightarrow 2\times 4=2|4-K|$
$\Rightarrow K=0\text{or}8$