Concentric Circle Problem Posted on June 18, 2015 by solvemymaths Someone at work showed me this today. I like it! Advertisements Share this:TwitterFacebookLike this:Like Loading... Related

Since the radius of the inner circle is arbitrary, make it zero, so the 10cm measurement is the orange circle’s diameter. Reply

Wouldn’t that make it half of a 10cm diameter circle’s area, which is to say 25/2 pi cm^2? In the other answers, it’s stated as 25pi, am I missing something?

That would make it half the area of a 10cm diameter circle, which would be 25/2 pi cm^2, but you state the answer as 25 pi. Am I missing something?

25 pi cm

yup

The area is surely in cm^2.

Since the radius of the inner circle is arbitrary, make it zero, so the 10cm measurement is the orange circle’s diameter.

Now that IS a smart approach!

Wouldn’t that make it half of a 10cm diameter circle’s area, which is to say 25/2 pi cm^2?

In the other answers, it’s stated as 25pi, am I missing something?

That would make it half the area of a 10cm diameter circle, which would be 25/2 pi cm^2, but you state the answer as 25 pi. Am I missing something?

Nevermind, I WAS missing something.

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Is the answer pi(10)^2?

25pi

25*pi