Question

If the circumference of a track is 40 cm, then match the portions of the track marked in red with its lengths.

• A. 10 cm
• B. 20 cm
• C. 40 cm

Answer 1

The perimeter of a circle is called its circumference.
The circumference of the track is given to be 40 cm.
$\therefore$ The length of the full circle is 40 cm.


$\therefore$ The length of the marked portion in the above image is 40 cm.


Only one-fourth of the circle is marked in red in the above image.

$\therefore \text{Length of portion in red}=\frac{\text{Circumference}}{4}$
$=\frac{40\text{cm}}{4}$
$=10\text{cm}$


Half of the circle is marked in red in the above image.

$\therefore \text{Length of portion in red}=\frac{\text{Circumference}}{2}$
$=\frac{40\text{cm}}{2}$
$=20\text{cm}$