Find surface area of a sphere

Question

There is a hollowed hemispere, where

Radius of outer sphere = 1.25cm

Diameter of inner sphere = 1.86

Find total surface area of the hemisphere

Plz, help me get an answer quick!

Answer 1

The formula of getting the surface area of the sphere is = 4πr²

 For surface area of a hemisphere use 2πr²

To get an area of hollowed hemisphere, you need to add outer surface area, inner surface area and area of ring.

Now you get:

        2π(1.25)²    +   2π(1.86/2)²  +  (  π(1.25)²  -  π(1.86/2)²  )

           3π(1.25)²  +  π(1.86/2)²

            3π(1.25)²  +  π(0.93)²

          14.71875  +   2.715786

                    17.43454

                     17.43 cm²

^{Hope this will help!}