Find the Area Difference: Circle with Radius r+2 vs Circle with Radius r

Circle O1 has a radius of r,
Circle O2 has a radius of r+2.

How much larger is circle O2 than circle O1?

r+2rO2O1

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Circle O1 has a radius of r,
Circle O2 has a radius of r+2.

How much larger is circle O2 than circle O1?

r+2rO2O1

2

Step-by-step solution

To solve this problem, we need to find the difference in areas between Circle O2 and Circle O1.

Step 1: Identify the given information
Circle O1 has a radius of rr
Circle O2 has a radius of r+2r + 2

Step 2: Recall the formula for the area of a circle
The area of a circle is given by the formula A=πr2A = \pi r^2, where rr is the radius.

Step 3: Calculate the area of Circle O1
A1=πr2A_1 = \pi r^2

Step 4: Calculate the area of Circle O2
A2=π(r+2)2A_2 = \pi(r+2)^2
We need to expand (r+2)2(r+2)^2:
(r+2)2=r2+4r+4(r+2)^2 = r^2 + 4r + 4
Therefore: A2=π(r2+4r+4)=πr2+4πr+4πA_2 = \pi(r^2 + 4r + 4) = \pi r^2 + 4\pi r + 4\pi

Step 5: Find the difference between the two areas
The difference in area is:
A2A1=(πr2+4πr+4π)πr2A_2 - A_1 = (\pi r^2 + 4\pi r + 4\pi) - \pi r^2
=πr2+4πr+4ππr2= \pi r^2 + 4\pi r + 4\pi - \pi r^2
=4πr+4π= 4\pi r + 4\pi

Step 6: Factor the result (optional)
We can factor out 4π4\pi:
4πr+4π=4π(r+1)4\pi r + 4\pi = 4\pi(r + 1)

Therefore, Circle O2 is larger than Circle O1 by an area of 4πr+4π4\pi r + 4\pi or equivalently 4π(r+1)4\pi(r+1).

3

Final Answer

4πr+4π4\pi r + 4\pi

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A circle has a circumference of 31.41.

What is its radius?

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