Question

from a solid cylinder whose height is 2.4 cm and diameter is 1.4 CM a conical cavity of the same height and same diameter is hollowed out find the total surface area of the remaining solid to the nearest centimetre square

Answer 1

Total surface area remaining solid = lateral surface area of cylinder + lateral surface of cone + area of base.
= 2πrh +πrl +πr2
= πr(2h+ l+r)
= 22/7×0.7 (2×2.4+2.5+0.7)
= 2.2(8)
= 17.6~18 cm2 (approx).