Question

What is the whole surface area of a cone of base radius 7 cm and height 24 cm?

Answer 1

$r = 7cm \: \\ h = 24cm \\ l = \sqrt{ {h}^{2} + {r}^{2} } \\ l = \sqrt{ {24}^{2} + {7}^{2} } \\ l = \sqrt{576 + 49} \\ l = \sqrt{625} \\ l = 25 \\ now \: \: \: \\ \: \: \: \: \: \: \: whole \: surface \: area \: of \: cone \\ \: \: \: \: \: \: \: \: = \pi \: r(l + r) \\ \: \: \: \: \: \: \: \: = \frac{22}{7} \times 7(25 + 7) \\ \: \: \: \: \: \: \: \: = 22 \times 32 \\ \: \: \: \: \: \: \: \: = 704 {cm}^{2}$