Question

The height of a right circular cylinder is 10.5 cm. If three times the sum of the areas of its two circular faces is twice the area of the curved surface area, find the radius of its base. Answer: 7 cm. Source: R.D Sharma. Please explain, final exam coming.

Answer 1

Let the radius be r

According to question

3 ( 2 pi r^2) = 2 ( 2 pi r h)

=> 6 pi r^2 = 4 pi r × 10.5

=> 6 r^2 = 42 r

=> 6r = 42

=> r = 7 cm

Radius of Base = 7 cm

Answer 2

Refer the attachment for the answer.