Question

A right cylinder just encloses a sphere. If the height of the cylinder is 21 cm find the surface area of cylinder

Answer 1

Dear Student,

◆ Answer -

Total surface area = 2079 cm^2

● Explanation -

As the cylinder just encloses the sphere, height of cylinder = diagonal of cylinder = diagonal of sphere.

Here, h = 21 cm, r = 21/2 = 10.5 cm

Total surface area = 2πr (r + h)

Total surface area = 2 × 22/7 × 10.5 × (10.5 + 21)

Total surface area = 2079 cm^2

Hence, the surface area of cylinder is 2079 cm^2.

Thanks dear. Hope this helps you...

Answer 2

The total surface area of the cylinder is 2097 sq. cm.

• The height of the cylinder is 21 cm.
• A right cylinder just encloses a sphere.
• Therefore, the diameter of the sphere is equal to the height of the cylinder.

Radius of the sphere = d/2 = 21/2 = 10.5 cm.

• Now, the total surface area of the cylinder = 2πr(r+h)

Total surface area of the cylinder = 2π(10.5)(10.5+21)

Total surface area of the cylinder = 2097 sq. cm.