a solid right cylinder is 18 cm high and the radius of the base is 7 cm two equal - Maths - Surface Areas and Volumes

Question

a solid right cylinder is 18 cm high and the radius of the base is
7 cm two equal right cones are drilled on the plane faces of the
cylinder , height of each cone being1/3rd the height of the
cylinder and the radius of base of each cone being equal to base of
the cylinder find the total surface area of the remaining solid

Shruti Tyagi · Accepted Answer

Dear Student,

The following figure can be drawn based on the statements given
<img alt="" src=
"https://s3mn%20mnimgs%20com/img/shared/ck-files/ck_58485de069209%20jpg"
style="width: 297px; height: 522px;">

Total surface area of the solid left = total surface area of cylinder - 2×Total surface area of cones
Total Surface area of cyclinder= 2πr(h+r)putting values in the aboave formula we getTotal Surface area of cyclinder= 2×227×7×(18+7)=44×25=1100

Total surface area of the cone=πr2+πrl
227×7×7+227×7×lwe can find l using pythagoras theoreml2=r2+h2l2=72+62l2=85l=85l=9
22Total surface area of cone227×7×7+227×7×9
2222×7+22×9 22356
84Total surface area of two cones2×356
84=713 68

Total surface area of solid left
=1100-713 68
=386 32

Regards,