Question

if slant height of a cone is 21 m and diameter of base is 24 m, then find its total surface area
​

Answer 1

Answer:

Slant height of cone is l=21 m.

Diameter of its base is d=24 m.

hence, radius of its base is r=

2

d

=12 m.

Now, the total surface area of cone is given by

S=πrl+πr

2

S=π(rl+r

2

)

S=π(12×21+12

2

)

S=π(252+144)

S=

7

22

×396

hence, S=1244.57 m

2

Answer 2

Step-by-step explanation:

Given,

Slant height of cone is l=21 m.

Diameter of its base is d=24 m.

hence, radius of its base is r=

2

d

=12 m.

Now, the total surface area of cone is given by

S=πrl+πr

2

S=π(rl+r

2

)

S=π(12×21+12

2

)

S=π(252+144)

S=

7

22

×396

hence, S=1244.57 m

2

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