Question

A toy in the form of cone of radius 3.5 cm mounted on a hemisphere of same radius. The total height of the toy is 15.5 cm, find the total surface area of toy.

Answer 1

Total surface area of toy $=$ Curved surface area of cone $+$ surface area of hemisphere

Curved surface area of cone $=$ $\pi rl$

Where $r=3.5cm$, Height $=15.5-3.5=12cm$

And hence, $l=12.5cm$ (by using formula $l^2=h^2+b^2$)

Therefore C.S.A. of cone $=\pi \times 3.5\times 12.5$

$=137.5c{m}^2$

Surface area of hemisphere $=2\pi r^2$

$=2\times \pi \times (3.5{)}^2$

$=77c{m}^2$

Hence T.S.A of toy $=77+137.5=214.5c{m}^2$