Question

Rasheed got a playing top (lattu) as his birthday present, which surprisingly had no colour on it. He wanted to colour it with his crayons. The top is shaped like a cone surmounted by a hemisphere (see Fig 13.6). The entire top is 5 cm in height and the diameter of the top is 3.5 cm. Find the area he has to colour. (Take π=22/7)

Answer 1

TSA of the toy = CSA of hemisphere + CSA of cone

Now, the curved surface area of the hemisphere

Also, the height of the cone = height of the top – height (radius) of the hemispherical part

You may note that ‘total surface area of the top’ is not the sum of the total surface areas of the cone and hemisphere.