Question

Find the curved surface area of a cone with radius 7 m and slant height 25 m.
(Take π = 22/7)
a 440 m2
b)660 m2
c)770 m2
d)550 m2

Answer 1

Given -

• Radius of the cone = 7m
• Slant height of cone = 25m

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To find -

• Curved surface area of the cone.

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Solution -

It is given that, there is a cone with radius and slant height of 7m and 25m respectively.

$\setlength{\unitlength}{1.2mm}\begin{picture}(5,5)\thicklines\put(0,0){\qbezier(1,0)(12,3)(24,0)\qbezier(1,0)(-2,-1)(1,-2)\qbezier(24,0)(27,-1)(24,-2)\qbezier(1,-2)(12,-5)(24,-2)}\put(-0.5,-1){\line(1,2){13}}\put(25.5,-1){\line(-1,2){13}}\multiput(12.5,-1)(2,0){7}{\line(1,0){1}}\multiput(12.5,-1)(0,4){7}{\line(0,1){2}}\put(18,1.6){\sf{7m}}\put(9.5,10){\sf{h}}\end{picture}$

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★ CSA (cone) = πrl ★

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$\tt\dashrightarrow{CSA_{(Cone)} = \dfrac{22}{7} \times 7 \times 25}$

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$\tt\dashrightarrow{CSA_{(Cone)} = 22 \times 25}$

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$\bf\dashrightarrow{CSA_{(Cone)} = 550m^2}$

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Therefore,

• The curved surface area of the cone is 550m².

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Hence,

• Option (d) is the correct option.

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Answer 2

Given :

• Radius ( r ) = 7m
• Height ( h ) = 25m

To Find :

• Curved surface area of a cone

Solution :

We've π = 22/7, r = 7m, l = 25m

By using formula,

⇒ CSA of a cone = πrl

⇒ CSA of a cone = 22/7 × 7 × 25

⇒ CSA of a cone = 22 × 25

⇒ CSA of a cone = 550 m²

So the correct option is d) 550 m²

•°• Hence, The curved surface area of a cone is 550 m²

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