Given: The perimeter of a semi-circle is 72cm Concept Used: The perimeter of the semi-circle is (πr + 2r) where r is the radius of the semi-circle Diameter = 2 × radius Calculation:
Perimeter of the semi-circle is 72cm (πr+2r)=72 ⇒r(π+2)=72 ⇒r(22/7+2)=72 ⇒r(36/7)=72 ⇒r=72×7/36 ⇒r=14 Radius of the semi-circle is 14cm Diameter = 2 × 14cm ⇒ 28cm ∴ The diameter of the semi-circle is 28cm