Answer
Answer A
Work Step by Step
$A(-3,4)$
$B(6, 3)$
$C(2, -1)$
$A_{ABC}=\pm\frac{1}{2}\begin{vmatrix}
-3 &4 & 1\\
6 & 3 & 1 \\
2 & -1 & 1
\end{vmatrix}$
$=\pm\frac{1}{2}[-3(3+1)-4(6-2)+1(-6-6)]$
$=\pm\frac{1}{2}(-12-16-12)$
$=\pm\frac{1}{2}.(-40)$
$=\pm(-20)$
Hence $A_{ABC}=20$.
The correct answer is A.
