\begin{definition}[Definition:Sign of Area of Triangle/Definition 2]
Let $\triangle ABC$ be a triangle embedded in the plane.
Let the sides of $\triangle ABC$ be traversed in the order of its vertices, that is:
:$AB \to BC \to CA$
If the area of $\triangle ABC$ is thus described in an anticlockwise direction, then $\triangle ABC$ is defined as having '''positive area'''.
If the area of $\triangle ABC$ is thus described in a clockwise direction, then $\triangle ABC$ is defined as having '''negative area'''.
Thus if a person $P$ were to walk around the boundary of $\triangle ABC$ in the direction $AB \to BC \to CA$ where $\triangle ABC$ has a '''positive area''', the interior of $\triangle ABC$ would be on the left of $P$.
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:Triangle $\triangle ABC$ with Positive Area
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:Triangle $\triangle ABC$ with Negative Area
\end{definition}