Question

Complete the table below

Sr. No.	Radius (r)	Diameter (d)	Circumference (c)
(i)	7 cm	....................	.................
(ii)	............	28 cm	..............
(iii)	..............	...............	616 cm
(iv)	...........	.............	72.6 cm

Answer 1

(i) Radius, r = 7 cm
Diameter, d = 2r = 2 × 7 = 14 cm
∴ Circumference, c = πd
= $\frac{22}{7}$ × 14
= 22 × 2
= 44 cm

(ii) Diameter, d = 28 cm
Radius, r = $\frac{d}{2}$ = $\frac{28}{2}$ = 14 cm
∴ Circumference, c = 2πr
= 2 × $\frac{22}{7}$ × 14
= 88 cm

(iii) Circumference, c = 616 cm
Now, c = 2πr (where 'r' is the radius)
⇒616 = 2 × $\frac{22}{7}$ × r
⇒r = 616 × $\frac{1}{2}$ × $\frac{7}{22}$
⇒r = 98
So, radius = 98 cm
Diameter, d = 2r = 2 × 98 = 196 cm

(iv) Circumference, c = 72.6 cm
Now, c = 2πr (where 'r' is the radius)
⇒72.6 = 2 × $\frac{22}{7}$ × r
⇒r = 72.6 × $\frac{1}{2}$ × $\frac{7}{22}$
⇒r = 11.55
So, radius = 11.55 cm
Diameter, d = 2r = 2 × 11.55 = 23.1 cm

The complete table is shown below.

Sr. No.	Radius (r)	Diameter (d)	Circumference (c)
(i)	7 cm	14 cm	44 cm
(ii)	14 cm	28 cm	88 cm
(iii)	98 cm	196 cm	616 cm
(iv)	11.55 cm	23.1 cm	72.6 cm