Question

What is the area of the semicircle whose diameter is $12$ mm? (Use $\pi =\pi$)

• A. $9\pi$ mm
• B. $18\pi$ mm
• C. $27\pi$ mm
• D. $36\pi$ mm

Answer 1

The correct option is B $18\pi$ mm

Area of the semicircle$=$ $\frac{1}{2}\pi r^2$
Diameter $=2\times$ radius
$\therefore$ radius $=$ $\frac{12}{2}=6$ mm
$=$ $\frac{1}{2}\times \pi \times 6^2$
$=$ $\frac{1}{2}\times \pi \times 36$
So, area of the semicircle $=$ $18\pi$ mm.