Monthly Archives: April 2024

$O$ is an interior point of regular hexgon $ABCDEF$. Prove that $[\triangle{OEF}]=2[\triangle{OAB}]+2[\triangle{OCD}]-3[\triangle{OBC}]$ Click here for the proof. Proof 1: Without loss of generality, assume that $ABCDEF$ is unit regular hexgon with its center at $(0,0)$, $A$ at $(-\dfrac{1}{2},-\dfrac{\sqrt{3}}{2})$, $B$ at … Continue reading →