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Find surface area of a sphere

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!
asked Aug 16, 2017 in Algebra by Adison

1 Answer

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


                     17.43 cm2

Hope this will help!

answered Aug 16, 2017 by quickwriter (2,510 points)