Help with finding the radius type of problem

momofmany75

New member
Joined
Mar 27, 2014
Messages
1
Hi there! Please excuse my ignorance but I have not done real Algebra or Geometry since high school. I have a problem here that I am stumped on. I have looked online and don't normally have a problem following a formula but this one is confusing me.

Basically I have to find the radius of a circle, for which, I have the circumference to.

The problem reads: The circumference of a circle is equal to 75 pi. Find the radius of the circle.

Well, to me, it looks like you are suppose to multiply 75 times pi but I know that isn't correct. So could this be a mistake? Was it written wrong? I know the formula is C=2 pi r. But that would mean that it would read 75 pi = 2 pi r. Doesn't that read 75 times pi? I have the answer. That would come to a very large number.

Please help!
 
momofmany75: That is correct: If C = 2*pi*r and C = 75*pi, then 2*pi*r = 75*pi. Is the problem in solving this for r?

Rich
 
You are told that the circumference is "75 times π\displaystyle \pi". You are NOT asked to find it. You should also know that "circumference=2πr\displaystyle 2\pi r" so you need to solve 2πr=75π\displaystyle 2\pi r= 75\pi for r.
 
Last edited:
Top