Length of Median of Triangle

Theorem
Let $\triangle ABC$ be a triangle.

Let $CD$ be the median of $\triangle ABC$ which bisects $AB$.


 * MedianOfTriangle.png

The length $m_c$ of $CD$ is given by:


 * ${m_c}^2 = \dfrac {a^2 + b^2} 2 - \dfrac {c^2} 4$