Question

Draw a graph for the radius and circumference of circles using a suitable scale.
[Hint Take radius=7, 14, 21 units and so on.]
From the graph,
Find the circumference of the circle when the radius is 42 units.

Answer 1

If radius is 7 units, then circumference of the circle = $2\times \pi \times 7$
$2\times \frac{22}{7}\times 7=2\times 22=44units[\because circumferenceofacircle=2\pi r]$
If radius is 14 units, then circumference $=2\times \pi \times 14=28\times \frac{22}{7}=88units$
If radius is 21 units, then circumference $=2\times \pi \times 21=42\times \frac{22}{7}=132units$
If radius is 28 units, then circumference $=2\times \pi \times 28=56\times \frac{22}{7}=176units$
If radius is 35 units, then circumference$=2\times \pi \times 35=70\times \frac{22}{7}=220units$
If radius is 42 units, then circumference $=2\times \pi \times 42=84\times \frac{22}{7}=264units$

Table for the graph,
$\begin{array}{ccccccc}Radiusofthecircle& 7& 14& 21& 28& 35& 42\\ Circumferenceofthecircle& 44& 88& 132& 176& 220& 264\end{array}$
Graph from the above data



The circumference of the circle will be 264 units when the radius is 42 units.