In a right circular cylinder, 4 times the sum of the areas of its two circular faces is twice the area of its curved surface. The height of a right circular cylinder is 6 m. Then the radius of the base is:
Solution
Correct Answer: Option A
Given that, 4 times the sum of the areas of two circular faces is twice the area of its curved surface. The height of a right circular cylinder is 6 m. we know that,
Area of curved surface of the cylinder = 2 π r h
Area of right circular face = π r2
Then, 4 × Sum of the areas of its two circular faces = 2 × Area of curved surface of the cylinder
⇒ 4 × (π r2 + π r2) = 2 ×2 π r h
⇒ 8 π r2 = 4 π r h
⇒ 2 r = h
Or, r = h/2 = 6/2 = 3 m.
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