Question

In Fig. 5, from a cubical solid metallic block, of dimensions 15cm X 10cm X5cm, a cylindrical hole of diameter 7 cm is drilled out. Find the surface area of the remaining block Use $\pi =\left(\frac{22}{7}\right)$

Answer 1

Surface area of the remaining block = Surface area of the cuboid + Curved surface area of cylinder
$=2(15\times 10+10\times 5+15\times 5)+(2\times \frac{22}{7}\times \frac{7}{2}\times 5)-(2\times \frac{22}{7}\times \frac{7}{2}\times \frac{7}{2})$
$=583c{m}^2$
Thus, the surface area of the remaining block is $583c{m}^2$.