Question

diameter of the base of a come is 10.5 and its slant height is 10vm ..find its curved surface area

answer☆`​

Answer 1

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$diameter \: of \: base = 10.5$

$\therefore \: radius \: of \: base \: r \: = \frac{10.5}{2}cm$

$\: \: \: \: \: = 5.25$

$slant \: height \: = 10cm$

$\therefore \: curved \: surface \: area \: of \: cone \:$

$\: \: \: \: \: \: \: \: \: = \pi \: rl$

$\implies \frac{22}{7} \times 5.25 \times 10$

$\implies \frac{22}{7} \times \frac{ 525}{100} \times 10$

$\implies \frac{22 \times 75 \times 10}{100}$

$\implies11 \times 5 = 165 {cm}^{2}$

Answer 2

Answer:

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Radius =

$\frac{diameter}{2}$

=$\frac{10.5}{2}$

${5.25cm}$

So, r=5.25cm

Slant height of cone is given as 10 cm.

So, I=10cm

Curved surface area of cone

=

$\pi \: rl = \pi \times 5.25 \times 10$

As we know,

$\pi = \frac{22}{7} \: and5.25 \\ can \ be \: written \: as \frac{525}{100}. \\ \\ so \: we \: get \\ \\ = \frac{22}{7} \times \frac{525}{100} \times 10 \\ \\ = 165cm$

Hence, the curved surface area of the cone is =

$165 {cm}^{2}$