Question

Find the circumferences of the circles from their diameters given below.

(1) 3.5 cm
(2) 6.3 m
(3) 0.14 m

Answer 1

(1) Diameter of the circle is 3.5 cm.
Circumference of a circle = 2πr
Or circumference = πd
Circumference = π × 3.5 cm
= $\frac{22}{7}\times 3.5=22\times 0.5$ $\left(\mathrm{Taking}\mathrm{\pi }=\frac{22}{7}\right)$
= 11 cm
∴ Circumference of the circle is 11 cm.

(2) Diameter of the circle is 6.3 m.
Circumference = πd
Circumference = π × 6.3 m
=$\frac{22}{7}\times 6.3=22\times 0.9$ $\left(\mathrm{Taking}\mathrm{\pi }=\frac{22}{7}\right)$
= 19.8 m
∴ Circumference of the circle is 19.8 m .

(3) Diameter of the circle is 0.14 m.
Circumference = πd
Circumference = π × 0.14 m
= $\frac{22}{7}\times 0.14=22\times 0.02$ $\left(\mathrm{Taking}\mathrm{\pi }=\frac{22}{7}\right)$
= 0.44 m
∴ Circumference of the circle is 0.44 m.