Question

Find the area of regular pentagon having length of the side as 5 cm and the radius of inscribed circle is 4.5 cm.

Answer 1

Side (a) of regular pentagon = 5 cm
Radius (r) of inscribed circle = 4.5 cm
Number of sides (n) = 5
∴ Area of regular polygon = $\frac{1}{2}\times n\times a\times r$

= $\frac{1}{2}\times 5\times 5\times 4.5$
= 56.25 cm²