Question

From a solid cylinder of height 15cm and diameter 16cm, a conical cavity of the same height and same diameter is hollowed out. find the total surface area of the remaining solid to nearest cm2.

Answer 1

h☆eya your answer is here☆

Even if the volume of a solid is hollowed out, its TSA remains the same,so to find the TSA of the cone,use the formula base area+CSA =πrl+πr2=πr(l+r).

Here, radius(r)=16/2=8cm,π=3.14

To find the slant height of the cone,we use the formula l2=r2+h2

l2=82+152

l2=64+225

l=√289=17

Now,TSA of cone[πr(l+r)]=3.14×8(17+8)

                                         =3.14×8×25

                                         =628 cm2

Therefore, total surface area of the remaining solid is 628 cm2.