Question

Find the T.S.A of a cone of radius 2r and slant height 1/2

Answer 1

slant height = l = 1/2
Radius = r = 2r

T.S.A of cone = πrl+ πr^2
= πr(l+r)
= π×2r ×[(1/2)+2r]
= π × 2r × (1+4r)/2
= πr(1+4r)
= πr+4πr^2
T.S.A = { (22/7)×r+ 4×(22/7)×r^2 }
= { 22r/7 + 88r^2/7 }
= (22r+88r^2)/7

Answer 2

The given slant height is 1/2.We can write that as l
and the given radius is 2r.We can write that as r

We know that,

The T.S.A of a cone is πrl+πr^2

Now,

T.S.A of the cone=πrl+πr^2

=π(rl+r^2)

=π{2r×1/2+(2r)^2}

=πr(1+4r)

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