# Find the surface area of a sphere of diameter 21 cm - Mathematics

Find the surface area of a sphere of diameter 21 cm

["Assume "pi=22/7]

#### Solution

"Radius (r) of sphere "= "Diameter"/2 =(21/2)cm=10.5cm

Surface area of sphere = 4πr2

=[4xx22/7xx(10.5)^2]cm^2

= 1386 cm2

Therefore, the surface area of a sphere having diameter 21 cm is 1386 cm2.

Concept: Surface Area of a Sphere
Is there an error in this question or solution?

#### APPEARS IN

NCERT Class 9 Maths
Chapter 13 Surface Area and Volumes
Exercise 13.4 | Q 2.2 | Page 225