Question

The ratio of the radii of two circles is 4:5. What is the ratio of the circumferences of the two circles? A. 16:25 B. pi:5 C. 4pi:5 D. 4:5

Answer 1

Answer:

Step-by-step explanation:

Aright, lets get started.

Suppose the radius of both circles are r1 and r2.

So, the circumference of both circles will be :

circumference of first circle = $2\pi r_{1}$

circumference of second circle = $2\pi r_{2}$

ratio of both circumference = $\frac{2\pi r_{1} }{2\pi r_{2} }$

ratio of both circumference = $\frac{r_{1} }{r_{2} }$

The ratio of both radius re given as 4:5, so plugging the value r1/r2

So, ratio of both circumference = $\frac{4}{5}$     ....   : Answer

Hope it will help :)

Answer 2

The ratio of the circumferences of the two circles is 4 / 5

Circumference of circle

C = 2πr

Where

• C is the circumference
• r is the radius

How to determine the circumference of each circle

Circle 1

• Radius of 1st circle (r₁) = 4
• Circumference (C₁) = ?

C₁ = 2πr₁

• C₁ = 2 × π × 4

C₁ = 8π

Circle 2

• Radius of 1st circle (r₂) = 5
• Circumference (C₂) = ?

C₂ = 2πr₂

C₂ = 2 × π × 5

C₂ = 10π

How to determine the ratio of the circumferences

• Circumference (C₁) = 8π
• Circumference (C₂) = 10π
• Ratio =?

Ratio = C₁ / C₂

Ratio = 8π / 10π

Ratio = 4 / 5

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