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.
Let r m be the radius, and h m be the height of the cylinder, then
r = 2.5 m and h = 21 m
Let r m be the radius and l m be the slant height of the cone, then
r1 = 2.5 m and l = 8 m
Now,
The Total Surface Area of the rocket
= C.S.A of cone + C.S.A of cylinder + Area of base
= r1l + 2 rh + r2
= rl + 2 rh + r2 [r1 = r]
= r (l + 2h + r)
(Use π = 3.14).