Mathematics

Problem

For a triangle with vertices

(x_1,y_1)

(x_2,y_2)

and

(x_3,y_3)

, let

D=\begin{vmatrix} x_1 & y_1 & 1\\ x_2 & y_2 & 1\\ x_3 & y_3 & 1 \end{vmatrix}

. Which of the following gives the area

\Delta

of the triangle in terms of

D

? a)

|D|

\dfrac{1}{4}|D|

\dfrac{1}{2}|D|

2|D|