Question

2. Find the surface area of a sphere of diameter:
(i) 14 cm (ii) 21 cm (iii) 3.5 m [NCERT EXERCISE)
( full explanation)​

Answer 1

Step-by-step explanation:

(i) diameter = 14 cm

r = 14/2 = 7cm

$surface \: area \: = \: 4\pi r^{2}$

= 4 × 22/7 × 7 × 7

$= 616cm ^{2}$

(ii) diameter = 21 cm

r = 21/2 = 10.5cm

surface area = 4 × 22/7 × 10.5 × 10.5

$= 1386cm ^{2}$

(iii) diameter = 3.5 cm

r = 3.5/2 = 1.75cm

$suface \: area \: = 4\pi r^{2}$

= 4 × 22/7 × 1.75 × 1.75

= 4 × 22/7 × 175/100 × 175/100

$= 38.5cm ^{2}$