Question

A bucket is in the shape of a frustum with the top and bottom circles of radii $15$cm and $10$cm. Its depth is $12$cm. Find its curved surface area and total surface area. (Express the answer in terms of $\pi$).

Answer 1

$R=15cm,r=10cm,h=12cm$$

$l=\sqrt{{(R-r)}^2+h^2}=\sqrt{{(15-10)}^2+{12}^2}=\sqrt{169}=13cm$

CSA = $\pi (R+r)l=\pi (15+10)\times 13=325\pi {cm}^2$

TSA = $\pi l(R+r)+\pi (R^2+r^2)=325\pi +\pi ({15}^2+{10}^2)$

= $325\pi +325\pi =650\pi {cm}^2$