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

pi r +(r+l)
22/7*12 (12+21)
22/7*396
22×56.5
1245.2

Answer 2

Given:-

• Slant height of the cone = 21 m

• Diameter of the base of cone = 24 m

To Find:-

• TSA of the cone

Solution:-

$\bf{Diameter = 24 cm}$

$\bf{Radius = ?}$

$\sf Radius \: = \: \dfrac{Diameter}{2}$

Slant height = 21 m

Substituting the values,

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

Radius = 12 cm

We know that,

${\orange{\sf TSA \: of \: the \: cone \: = \: \pi r(r \: + \: l) \: units^2}}$

Substituting the values,

$\sf TSA \: of \: the \: cone \: = \: \dfrac{22}{7} \: * \: 12 \: (12 \: + \: 21) \: m^2$

$\sf TSA \: of \: the \: cone \: = \: 3.14 \: * \: 12 \: (33) \: m^2$

$\sf TSA \: of \: the \: cone \: = \: 3.14 \: * \: 12 \: * \: 33 \: m^2$

$\sf TSA \: of \: the \: cone \: = \: 1243.44 \: m^2$

Therefore,

$\sf{TSA ~of ~a ~cone = 1243.44 m^2.}$