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.
|Total Surface area of Sphere (TSA) = 4πr2|
|Curved Surface area of Hemisphere(CSA) = 2πr2|
|Total Surface area (TSA) = 3πr2|
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.
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