\begin{definition}[Definition:Sign of Area of Triangle/Definition 1]
Let $\triangle ABC$ be a triangle embedded in the plane.
Let $\theta$ be the angle between $AB$ and $AC$.
If the direction of $\theta$ is anticlockwise, then $\triangle ABC$ is defined as having '''positive area'''.
If the direction of $\theta$ is clockwise, then $\triangle ABC$ is defined as having '''negative area'''.
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:Triangle $\triangle ABC$ with Positive Area
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:Triangle $\triangle ABC$ with Negative Area
\end{definition}