Question

A decorative block shown in figure, is made of two solids- a cube and a hemisphere. The base of the block is a cube with edge $5cm$, and the hemisphere fixed on the top has a diameter $4.2cm$. Find the total surface area of the block (Take $\pi =22/7$)

Answer 1

We have

Edge of cube= 5 cm

Diameter of hemisphere= 4.2 cm

Clearly

Surface area of decorative block

$=$ total surface area of the cube - base area of hemisphere + curved surface area of hemisphere

$=(6\times (edge{)}^2-\pi r^2+2\pi r^2){cm}^2$

$=(25\times 6+\pi r^2){cm}^2$

$=\{150+\frac{22}{7}\times {\left(2.1\right)}^2\}{cm}^2$

$=163.86{cm}^2$