Question

The diameter of a semicircular protractor is 7cm. Find its perimeter

Answer 1

Step-by-step explanation:

$Diameter \: of \: protractor \: d =7 \: cm \\ \therefore \: radius \: r = \frac{7}{2} \: cm\\ Perimeter \: of protractor\\=\frac{1}{2}\times circumference \: of \: circle + diameter \\=\frac{1}{2}\times 2\pi r +d\\ = \pi \: r + d \\ = \frac{22}{ 7} \times \frac{7}{2} + 7 \\ = \frac{22}{2} + 7 \\ = 11 + 7 \\ = 18 \: cm \\ thus \: the \: perimeter \: of \: protractor \: \\ is \: 18 \: cm. \:$

Answer 2

Answer:

Let r be the radius of the protractor.

$then \: \: \: \: \: r = \frac{1}{2} cm \\ \\ perimeter = \frac{1}{2} (circumference) + diameter \\ \\ = \frac{1}{2} \times 2\pi \: r + 2r \\ = \pi \: r + 2r \\ = r(\pi + 2) \\ \frac{7}{2} ( \frac{22}{7} + 2)cm \\ \\ = \frac{7}{2} ( \frac{36}{7} )cm = 18cm$

✅ hence the perimeter of the protector is 18cm.

hope it helps you ⛄