A circular shaped ball with a diameter or radius is called a sphere.A diameter which is a straight line through the center of a sphere and with the end points on the boundary is called its diameter.
The section of the sphere by the plane is called a hemisphere. Let’s see how to find the area of Hemisphere.
Formula of Surface area of Hemisphere.
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Total Surface area of Sphere (TSA) = 4Ï€r2 |
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Curved Surface area of Hemisphere(CSA) = 2Ï€r2 |
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Total Surface area (TSA) = 3Ï€r2 |
Surface area of Hemisphere Formula Examples
Question: The radius of a red balloon increases from 6cm to 12 cm when the air is pumped into it. Calculate the ratios of the surface areas of the balloon in both the cases.
Solution:
First the radius of the balloon = 6 cm
Second the radius of the balloon = 12 cm
Surface Area of a hemisphere = 3*pi*radius ^2
The ratio of the surface areas will be
= 3*pi*(6)2 : 3*pi*(12)2
= 62 : 122
= 36 : 144
= 1 :4
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