SOLUTION: The sum of the areas of two circles is 106π cm^2 and the radius of the larger circle is 4cm longer than the radius of the smaller circle. Find the lengths of the radii.

Algebra ->  Surface-area -> SOLUTION: The sum of the areas of two circles is 106π cm^2 and the radius of the larger circle is 4cm longer than the radius of the smaller circle. Find the lengths of the radii.      Log On


   

Question 1116390: The sum of the areas of two circles is 106π cm^2 and the radius of the larger circle is 4cm longer than the radius of the smaller circle. Find the lengths of the radii.
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
Radii, r and r+4

pi%2Ar%5E2%2Bpi%2A%28r%2B4%29%5E2=106pi
r%5E2%2B%28r%2B4%29%5E2=106
r%5E2%2Br%5E2%2B8r%2B16-106=0
2r%5E2%2B8r-90=0
r%5E2%2B4r-45=0
%28r-5%29%28r%2B9%29=0
highlight%28r=5%29--------radius of the small circle
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highlight%289%29----------radius of the big circle