Mathematics: The total surface area of a cone whose radius is 2 r and slant height 2l is (A) 2πr (l + r)(B) πr (l + 4 r )(C) πr (l + r)(D) 2πrl

10Step-by-step explanation:i took the test...

The total surface area of a cone whose radius

meaghan18

14.02.2022

$A=4\pi r(l+r)$

Step-by-step explanation:

The total surface area of a cone is given by :

$A=\pi rl+\pi r^2\\\\=\pi r(l+r)$

Put r = 2r and l = 2l in the above formula

$A=\pi \times 2r(2l+2r)\\\\A=2\pi r(2l+2r)\\\\=2\pi r \times 2(l+r)\\\\=4\pi r(l+r)$

Hence, the total surface area of the cone is $4\pi r(l+r)$ .

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Luchi8115

23.01.2021

Step-by-step explanation:

i took the test

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