Question

If the radius and slant height of a cone are r/2 and 21. Then find its total surface area.

Answer 1

Slant height =2l
Radius =r/2


T. S. A of cone = 2π×r(r+l)

2π× r/2 ( r/2 + 2l)

π× r ( r + 4l) /2




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Answer 2

radius,r=r/2
slant height,l=21
total surface area of cone=πr(l+r)
=22/7×r/2(21+r/2)
=11r/7[(42+r)/2]
=(462r+11r^2)/14
$(462r+11r^2)/14$

=11r(42+r)/14
$11r(42+r)/14$