Find the surface area (in cm 2 ) of a sphere whose diameter is 21 cm.

SSC GD Constable 6 Feb 2025 Shift 2 Paper

Section: Elementary Mathematics

Question : 42 of 80

Marks: +1, -0

Find the surface area (in cm²) of a sphere whose diameter is 21 cm.

Solution:

Surface Area of Sphere

=4 π r^2

Where,

r =

radius of the sphere
Calculation:
Radius

( r )=

Diameter

÷ 2

⇒ r =21 ÷ 2=10.5 cm

Surface Area

=4 × π × r^2

⇒ Surface Area

=4 × 22 \/ 7 ×(10.5)^2

⇒ Surface Area

=1386 cm^2

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