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'Circled Corners' printed from https://nrich.maths.org/
The three angles of the triangle add to $180^{\circ}$, so the combined area of the three sectors of the circles that are inside the triangle add up to half a circle with area:
$\frac{1}{2} \times \pi \times 2^2 = \frac {4\pi}{2}= 2\pi$.
So the grey area is $(80- 2\pi) cm^2$.