Question

There is a coin. Ram attaches a hemispherical attachment to one flat end of the coin which has the same radius as the coin. What is the surface area of the combined solid?

• A. Coin T.S.A + Hemisphere T.S.A + Coin base area
• B. Coin T.S.A - Coin base area + Hemisphere C.S.A
• C. Coin base area + Coin C.S.A + Hemisphere C.S.A
• D. Coin T.S.A + Hemisphere T.S.A

Answer 1

The correct option is C

Coin base area + Coin C.S.A + Hemisphere C.S.A

The diagram below gives a side view of the combined solid.

The diagram below gives a top view of the combined solid.

The combined solid has the following surfaces-

One flat surface of the coin, one curved surface of the coin and the curved surface of the hemisphere

These 3 areas together to gives the total surface area of the combined solid.