Mensurationhard · Past Paper
What is the total surface area of a solid cone if its radius is r/2 and slant height is 2l?
Aπr(l + r/4)
Bπr(l + r)
C2πr(l + r)
Dπr(l + r/2)
✓ Correct Answer: A — πr(l + r/4)
TSA = πR(R+L). Here R=r/2, L=2l. TSA = π(r/2)(r/2 + 2l) = πr/2 * (r + 4l)/2 = πr(r + 4l)/4 = πr(l + r/4).
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