Question

the ratio between the radii of two circles is 5 : 7. find the ratio between their circumference and area

Answer 1

Hello,
The raddi of two circles=5x,7x
the ratio of circumference's=2×pie×r/2×pie×r
(2×22/7×5x)/(2×pie×r)
=5/7
ans.5:7

Answer 2

The ratio between their circumference and area is 5: 7 and 25:49 respectively.

Step-by-step explanation:

The ratio between the radii of two circles is 5 : 7

Let the ratio be x

Radius of circle 1 = 5x

Area of circle 1 = $\pi r^2 = \frac{22}{7} \times (5x)^2$

Radius of circle 2 = 7x

Area of circle 2 = $\pi r^2 = \frac{22}{7} \times (7x)^2$

So, ratio of their areas = $\frac{\frac{22}{7} \times (5x)^2}{\frac{22}{7} \times (7x)^2} = \frac{25}{49}$

Circumference of circle 1 = $2 \pi r = 2 \times \frac{22}{7} \times 5x$

Circumference of circle 2 = $2\pi r = 2 \times \frac{22}{7} \times 7x$

ratio of their circumferences = $\frac{2 \times \frac{22}{7} \times 5x}{2 \times \frac{22}{7} \times 7x} = \frac{5}{7}$

Hence the ratio between their circumference and area is 5: 7 and 25:49 respectively.

#Learn more:

The circumferences of two circles are in the ratio 5:7,find the ratio between their radii

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