Question

A cone has a circular base of radius 10 cm and slant height of 30 cm. Calculate the suraface area

Answer 1

Answer :

Given radius of cone ( r ) = 10 cm

Given slant height ( l ) = 30 cm

Surface area of cone = πr( l + r )

$\pi \times 10(30 + 10) \\ \\ = > \frac{22}{7} \times 10(30 + 10) \\ \\ = > \frac{22}{7} \times 10 \times 40 \\ \\ = > \frac{22}{7} \times \frac{10}{1} \times \frac{40}{1} \\ \\ = > \frac{22 \times 10 \times 40}{7 \times 1 \times 1} \\ \\ = > \frac{22 \times 400}{7} \\ \\ = > \frac{8800}{7} \\ \\ = > 1257.142 \: cm \: (approx) \\ \\ if \: we \: put \: \pi = 3.14 \: \\ then \: surface \: area \: = > \\ \\ 3.14 \times 10(30 + 10) \\ \\ 3.14 \times 10 \times 40 \\ \\ 1256 \: cm \: \\ \\ so \: both \: are \: correct \:so \: you \: \\ can \: take \: both$


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