Question

A hemi-spherical dome of a building needs to be painted. If the circumference of the base of the dome is 17.6 cm, find the cost of painting it, given the cost of painting is Rs 5 per 100 cm².

Answer 1

In the given problem, a hemispherical dome of the building needs to be painted. So, we need to find the surface area of the dome.

Here, we are given the circumference of the hemispherical dome as 17.6 m and as we know that circumference of the hemisphere is given by. So, we get

So, now we find the surface area of the hemispherical dome.

So, the curved surface area of the dome is 49.28 m²

Since the rate of the painting is given in cm², we have to convert the surface area from m² to cm².

So, we get

Curved surface area =

= 492800 cm²

Now, the rate of painting per 100 cm² = Rs 5

The rate of painting per 1 cm² =

So, the cost of painting the dome =

Therefore, the cost of painting the hemispherical dome of the building is