We have learnt that length of a side of the regular hexagon drawn inside a circle will be equal to the radius of the circle. So the radius of the circle will be 20 cm.
Area of the circle = πr2 = π × 20 × 20 = 400π
= 1256 cm2
Area of the regular hexagon \(=\frac{6\times\sqrt{3}\times a^2}{4}\)
Area of shaded portion = 1256 – 1039.2 = 216.8 cm2