Question

f slant height of the cone is 21cm and diameter of base is 24 cm. The total surface area of cone is: *

1200.77 sq.cm
b. 1177 sq.cm
c. 1222.77 sq.cm
d. 1244.57 sq.cm

Answer 1

Given -

• Slant height(l) of the cone =21cm
• Diameter (d) of the base = 24cm

To find -

• Total surface area (T. S. A) of the cone

Solution -

Here,

Diameter (d) = 24cm

$radius(r) = \frac{d}{2}$

$radius(r) = \frac{24}{2} = 12cm$

We know that,

$T. S. A \: of \: cone = \pi \: r(l + r)$

Putting the values we will get -

$T. S. A \: of \: cone = \frac{22}{7} \times 12(21 + 12)$

$T. S. A \: of \: cone = \frac{264}{7} \times 33$

$T. S. A \: of \: cone = \frac{8712}{7}$

$T. S. A \: of \: cone = 1244.57$

Therefore total surface of the cone is 1244.57 cm²

Related Formulae -

$1)Volume \: of \: cone = \frac{1}{3} \pi {r}^{2} h$

$2)Curved \: Surface \: Area(C. S. A ) \: of \: cone \: = \pi \: rl$

$3)Total \: Surface \: Area(T. S. A ) \: of \: cone = \pi \: r(l + r)$