Question

find the total surface area of cone if its slant height is 21 m and diameter of its base is 24 m .

Answer 1

given slant height H= 21 m

and diameter=24m

so radius= D/2= 24/2= 12m

now total surface area of cone=πrl

now l = slant height

so 22/7×12×21=792m^2

hope it help you

Answer 2

Answer:

Radius = $\sf\dfrac{24}{2}\:$ = 12 m

Slant height (l) = 21 m

Total surface area of cone :

$\\ \sf \: \pi \: r \: ( \: r + l \: ) \\ \\ \\ \implies \sf \: \frac{22}{7} \times 12 \times 33 \: \: {m}^{2} \\ \\ \\ \implies \sf \: \frac{22}{7} \times 12 \times 33 \: {m}^{2} \\ \\ \\ \implies \sf \: 1244.57 \: \: {m}^{2}$