Question

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

Answer 1

Step-by-step explanation:

HEY MATE ......

$given \: \\ \\ slant \: height \: of \: cone \: is \: = 21m \\ d \: of \: its \: base \: = 24m \\ \\ hence \: radius \: of \: its \: base = r = \frac{d}{2} = 12m \\ \: now \: the \: total \: surface \: of \: cone \: is \: \\ \\ s = \pirl + \pi {r}^{2} \\ s = \pi(rl + {r}^{2} ) \\ s = \pi(12 \times 21 + {12}^{2} ) \\ s = \pi(252 + 144) \\ s = \frac{22}{7} \times 396 \\ hence \: s = 1244.57 {m}^{2}$

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Answer 2

Answer:

Given: l= 21cm

d = 24 cm

Hence ,

r =d/2 = 12cm

To find : Total surface areas of the cone

Solution:

l = 21cm ...........(Given)

r = 12cm ..,........(Given)

Total surface area of the cone = πr ( l+r)

= 3.14 ×12 ( 21+12)

= 314/100 ×12 (33)

= 6.56 ×177

= 1161.12 cm²