Question

the radius of a circle is 3.5cm. find the perimeter of the quarter of a circle, correct to one decimal place.

Answer 1

Radius of the circle = 3.5cm

The total perimeter of the circle

2×$\bf\huge\frac{22}{7}$ × r = 21.99 cm

Perimeter of quarter of the circle.

=  $\bf\huge\frac{2\times \frac{22}{7}\times r }{4}$ = 5.49 cm

Perimeter of the figure

= $\bf\huge\frac{2\times \frac{22}{7}\times r }{4}$ + 3.5 + 3.5

= 12.5 cm

Answer 2

Radius = 3.5cm

It is a quarter circle.

So, Perimeter = Circumference of Circle + Radius + Radius

Circumference
$= \frac{1}{4} \times 2\pi \: r$
$\frac{3.5 \: \pi}{2 } \\ \\ = \frac{ \frac{35}{10} \times \frac{22}{7} }{2} \\ \\ = \frac{11}{2} = 5.5cm$
Perimeter = 5.5 + 3.5 + 3.5
= 12.5cm