Question

Find the total surface area of
the cone, find its slant height
is 21m and diameter of its ba
se 24.
​

Answer 1

The Total Surface Area of the Cone = 1,244.57 m².

Step-by-step explanation:

$\\ \sf \large \purple{Given}$

• Slant height of the Cone = 21 m .
• Diameter of its base = 24 m

So, it's Radius = 24/2 = 12 m .

$\\ \sf \large \purple{To \: find}$

• Total Surface Area of the Cone .

$\\ \sf{ \large \purple{ Formula \: used} } : - \: \underline{\boxed{ \sf \pi r(r + l)} }$

$\sf \large \purple{Solution}$

$\sf \: Total \: Surface \: Area \: of \: Cone = \pi rl$

$\blue{:\implies}\sf \dfrac{22}{7} \times 12 (12 + 21)$

$\blue{:\implies}\sf \: \dfrac{22}{7} \times 12 \times 33$

$\blue{:\implies}\sf \: \dfrac{8712}{ 7}$

$\blue{:\implies} \boxed { \sf \: 1,244.57 \: {m}^{2} }$

Hence the Total Surface Area of the Cone = 1,244.57 m².

Some Formula related to Cone :-

• C.S.A of the Cone = πrl
• T.S.A of the Cone = πr( r + l )
• Volume of the Cone = ⅓ πr²h