Question

find tha total surface area of a cone ,if it's slant height is 21 m and diameter of it's base is 24 m.​

Answer 1

Given:-

• Slant height of cone = 21 m.
• Diameter of it's base = 24 m.

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To find:-

• Total surface area of cone.

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Solution:-

Therefore,

$\huge{\tt{\longmapsto{Radius = 12 m}}}$

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★ As we know,

$\star{\large{\boxed{\sf{\orange{T.S.A~ of~ cone = \pi r(l + r)}}}}}$

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$\huge{\tt{\longmapsto{\dfrac{22}{7}\times 12(21 + 12)}}}$

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$\huge{\tt{\longmapsto{1244.57 m^2}}}$

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Hence, total surface area of cone is 1244.57 m².

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Answer 2

Given

• Slant height of the cone = 21 m
• Diameter of it's base = 24 m
• Radius = 12 m

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To find

• Total surface area of the cone.

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Solution

• By using the formula (Total surface area) of cone.

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$\: \: \: \: \: \: \: \: \: \: \: \: \boxed{\tt{\bigstar{T.S.A_{(Cone)} = \pi r(l + r){\bigstar}}}}$

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Here,

• r = 12 m
• l = 21 m

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$\tt\longmapsto{T.S.A = \dfrac{22}{7} \times 12(21 + 12)}$

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$\tt\longmapsto{T.S.A = \dfrac{22}{7} \times 12(33)}$

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$\tt\longmapsto{T.S.A = \dfrac{22}{7} \times 396}$

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$\tt\longmapsto{T.S.A = \dfrac{8712}{7}}$

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$\bf\longmapsto{T.S.A = 1244.57m^2}$

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Hence,

• Total surface area of the cone is 1244.57 m².

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