If the diameter of a circle changes from 18 cm to 6 cm, how will the circumference change?

Question

asked Jun 19, 2019 196k views

2 Answers

Fdetsch · Answer 1 · 2019-06-25T14:08:48+0000

Answer:

The circumference of a circle is changes by
(1)/(3) .

Explanation:

Formula

$Circumference\ of\ a\ circle = 2\pi r$

Where r is the radius of the circle .

As given

If the diameter of a circle changes from 18 cm to 6 cm .

Initial diameter = 18 cm

$Initial\ radius = (Initial\ diameter)/(2)$

$Initial\ radius = (18)/(2)$

= 9 cm

$\pi = 3.14$

$Circumference\ of\ initial\ circle = 2* 3.14* 9$

= 56.52 cm

Final diameter = 6 cm

$Final\ radius = (Initial\ diameter)/(2)$

$Final\ radius = (6)/(2)$

= 3 cm

$\pi = 3.14$

$Circumference\ of\ final\ circle = 2* 3.14* 3$

= 18.84 cm

Thus

$(Circumference\ of\ final\ circle)/(Circumference\ of\ initial\ circle) = (18.84)/(56.52)$

$(Circumference\ of\ final\ circle)/(Circumference\ of\ initial\ circle) = (1)/(3)$

Therefore the circumference of a circle is changes by
(1)/(3) .