Question

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

Answer 1

Hello!

• Slant height, l = $\bf{21\: m}$
• Radius of the base, r = $\dfrac{24}{2}$ = $\bf{12 \:m}$

Then,

$\underline{\bf{Total\:curved\:surface\:area\:of\:Cone}}$ :

$\sf πr(l+r) \\ \\ \implies \dfrac{22}{7} \times 12 \times (21+12) \\ \\ \implies \dfrac{22}{7} \times 12 \times 33 \\ \\ \implies \dfrac{8712}{7} \sf m \implies \boxed{\red{\bf{1244.6 \:m}}}$

Cheers!

Answer 2

diameter=24

radius=24/2=12 m

slant height(l)= 21 m

total surface area = πr(r+l)

                              =3.14*12*(12+21)

                             =3.14*12*33

                              =1243.44m