The decorative block shown in fig. is made of two solids - a cube and a hemisphere. The base of the block is a cube with edge 5 cm, and the hemisphere fixed on the top has a diameter of 4.2 cm. Find the total surface area of the block.
We have, r1 = Radius of the base of the cylinder = 7m
r2 = Radius of the base of the cone = 7 m
h1 = Height of the cylinder = 6m
In right triangle EOC, we have
Thus, slant height (CE) = 14 m
Now,Surface area of building = Curved surface area of cylinder + curved surface area of cone
Cost of painting the building from inside at the rate of Rs. 30/m2
= Rs. (572 x 30) = Rs. 17160.
(Use π = 3.14).