Courses
Courses for Kids
Free study material
Free LIVE classes
More

A toy is in the shape of a right circular cylinder with a hemisphere on one end and a cone on other. The radius and height of the cylindrical part are$5cm$ and$13cm$ respectively. The radii of hemisphere and conical parts are the same as that of the cylindrical part. Find the surface area of the toy if the total height of the conical part is$12cm$.

Last updated date: 24th Mar 2023
Total views: 218.2k
Views today: 4.95k
Height of cylindrical part,$h$ $= 13cm$
Radius of cylindrical part,$r$ $= 5cm$
The radii of the spherical part and base of the conical part are also $r$.Let us suppose ${h_1}$ be the height of the conical part and $l$ be the slant height of the conical part.
${l^2} = {r^2} + {h_1}^2 \\ \Rightarrow l = \sqrt {{r^2} + {h_1}^2} \\ \Rightarrow l = \sqrt {{5^2} + {{12}^2}} = 13cm \\$
Now, the surface area of the toy$=$ curved surface area of the cylindrical part$+$ curved surface area of the hemispherical part$+$ curved surface area of the conical part.
$= \left( {2\pi rh + 2\pi {r^2} + \pi rl} \right)c{m^2} \\ = \pi r\left( {2h + 2r + l} \right)c{m^2} \\ = \left( {\dfrac{{22}}{7} \times 5 \times \left( {2 \times 13 + 2 \times 5 + 13} \right)} \right)c{m^2} \\ = 770c{m^2} \\$
Therefore, the surface area of the toy$= 770c{m^2}$