A regular hexagon is inscribed in a circle of radius 6 cm. Its area is:

The six radii cut the hexagon into six triangles, each with two sides of 6 cm and an included angle of 360°/6 = 60°. Each has area $(1/2)(6)(6)$·sin60° = 9√3, so the hexagon is $6\times 9$√3 = 54√3 ≈ $93.5{\text{cm}}^2$. Forgetting the (1/2) in the area formula doubles it to 108√3.