Question

In figure, from a cuboidal solid metalic block, of dimensions $15cm\times 10cm\times 5cm$, a cylindrical hole of diameter $7cm$ is drilled out. Find the surface area of the remaining block. (Take $\pi =22/7$)

Answer 1

Surface area of remaining block = Surface area of cuboid + Curved surface area of cylinder - $2\times$ area of base

$=A_I+A_{II}$

$A_{II}$ $=2\pi \left(3.5\right)5-2\pi (3.5{)}^2=$ $33c{m}^2$

$A_I=2(15\times 10+10\times 5+5\times 15)$=$2\times 275=550c{m}^2$

$A_{total}=583c{m}^2$