calculate the surface area of cone whose siant height is 21 m and diameter is 24 m
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Answer:
Slant height of cone is l=21 m.
Diameter of its base is d=24 m.
hence, radius of its base is r = d/2
=12 m.
Now, the total surface area of cone is given by
S=πrl+πr ²
S=π(rl+r²)
S=π(12×21+12²)
S=π(252+144)
S= 22/7 ×396
S=1244.57 m²
Surface Area = 1244.57 m²
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Solution :
Diameter of Cone = 24 m
> Radius of cone = 12 m.
The slant height of this cone is 21 m.
Let us assume that the height of the cone is h m.
> h^2 + (12)^2 = (21)^2
> h^2 = (21)^2 - (12)^2
> h^2 = (33)(9)
h = 3 root 33 .
To find : Total surface area of the cone
> pi r l + pi r^2
r = 12 cm and l = 21 cm
> pi * 12 * 21 + pi * 21 * 21
> 252 pi + 441 pi
> 693 pi
> 693 * 22/7
> 2178 m^2 .
This is the required answer
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