Question

FROM A CUBOIDAL BLOCK OF DIMENSIONS 15 × 10 × 5CM ,A CYLENDRICAL HOLE OF DIAMETER 7CM IS DRILLED OUT. FIND THE SURFACE AREA OF THE REMAINING SOLID BLOCK

Answer 1

surface area of block before hole..2(lb +bh +hl)
2( 15*10+10*5+15*5)
2(150+50+75)
2(325)
750cm²

surface area of whole
nr² =22/7*7/2*7/2
22*2*2/7
88/7
12.5cm²
subtract both
750cm²-12.5cm²

737.5cm²