Question

A flower pot in the shape of a frustum cone with the top and bottom circles of radii $20$m and $40$m. It's depth is $15$in. Find its surface area.

• A. $3100$ $m^2$
• B. $3400\pi$ $m^2$
• C. $3500$ $m^2$
• D. $3500\pi$ $m^2$

Answer 1

The correct option is D $3500\pi$ $m^2$

If top and bottom radius of the frustum is $R$ snd $r$, then its surface area id given as,

Surface area = $\pi (R+r)\sqrt{(R-r{)}^2+h^2}+\pi r^2+\pi R^2$

$=\pi (40+20)\sqrt{(40-20{)}^2+{15}^2}+\pi {20}^2+\pi {40}^2$

$=\pi \left(60\right)\sqrt{400+225}+\pi 400+\pi 1600$

$=\pi \times [60\times 25+2000]$

$=3500\pi$ $m^2$