7.0 Area of triangle

If $A({x_1},{y_1}),{\text{ }}B({x_2},{y_2}){\text{ and }}C({x_3},{y_3})$ are the vertices of a $\Delta ABC$, then its area can be calculated using the formulae

\[{\text{Area = }}\frac{1}{2}{\text{ }}\left| {\begin{array}{c}{{x_1}}&{{y_1}}&1 \\ {{x_2}}&{{y_2}}&1 \\ {{x_3}}&{{y_3}}&1 \end{array}} \right|\]

provided the vertices are taken in the counter clockwise sense.