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Expert: Steve Holleran - 8/12/2008


Question

find radius
should I use trigonometrics to solve it or is a geometry problem, thanks.

Answer
Hi Pablo,

I would definitely use geometry.

There is a theorem about chords in a circle which states that when two chords intersect inside a circle, the product of the segments on the one chord is equal to the product of the segments on the other chord.

So, if I'm reading the diagram correctly, you would have

          5 * 2x = (3x-2) * x

            10x  = 3x^2 - 2x

              0  = 3x^2 - 12x   

              0 =  3x(x - 4)     so x = 0 or 4.  Throw out the 0.

So, if x = 4 then 2x = 8 and the diameter in the diagram is 8 + 5 = 13, so that means the radius has to be 6.5.


Hope this is what you needed.
Steve
    Questioner's Rating
    Rating(1-10)Knowledgeability = 10Clarity of Response = 10Politeness = 10
    Commentthanks a lot steve, itīs absolutely clear now.


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Steve Holleran

Expertise

I can help with all math questions from basic math to Calculus. Whether it`s consumer questions, or questions from high school or college students, I have probably dealt with it at some time in my career.

Experience

33 years teaching experience in NJ public schools

Education/Credentials
B.S. Mathematics : Wake Forest University 1972 M.S. Mathematics : Monmouth University 1981

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