SEAMO 2027 - Paper E - SET 04 - Self-study Question 15

In the diagram, $ABC$ is isosceles with $AB=AC$. Points $M,N$ are the midpoints of $AB,AC$, respectively. Given $CM\perp BN$, $BC=20\text{ cm}$ and $[ABC]=x\text{ cm}^2$, find $x$.



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