Question

How to do the circumference of a semicircle with a radius of 7 1/2.

Answer 1

• Radius=r=7.5units

Circumference

• πr+2r
• r(π+2)
• 7.5(3.14+2)
• 7.5(5.14)
• 38.6units²

Answer 2

38.6 units (nearest tenth)

Explanation:

Formulae

• Diameter = 2r
• Circumference = 2πr

(where r is the radius)

Circumference of a semicircle = diameter + half the circumference

⇒ Circumference of a semicircle = 2r + πr

Given:

• 
  `\sf radius\:{(r)=7\frac12=7.5`

`\begin{aligned}\implies \textsf{Circumference of semicircle} & = 2(7.5) + \pi(7.5)\\ & = 15+7.5 \pi\\ & = 38.5619449...\\ & = 38.6\:\sf units\:(nearest\:tenth)\end{aligned}`