W
where_mytruelove


Cho tam giác ABC:
CMR: [TEX]S= \frac{1}{2}\sqrt{\vec{AB}^{2}.\vec{AC}^{2}-2(\vec{AB}.\vec{AC})^{2}}[/TEX]
~X(
CMR: [TEX]S= \frac{1}{2}\sqrt{\vec{AB}^{2}.\vec{AC}^{2}-2(\vec{AB}.\vec{AC})^{2}}[/TEX]
~X(
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