document.write( "Question 1133040: Hello!
\n" ); document.write( "What is the radius of a sphere whose area is equal to the sum of the areas of four circles of radius 7?
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Algebra.Com's Answer #750202 by greenestamps(13200) $\"\"$ $\"About$

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\n" ); document.write( "The area of a circle is $\"%28pi%29%28r%5E2%29\"$ .

\n" ); document.write( "The area of 4 circles each with the same radius is $\"4%28pi%29%28r%5E2%29\"$ .

\n" ); document.write( "The surface area of a sphere is $\"%284pi%29%28r%5E2%29\"$ .

\n" ); document.write( "Those last two area formulas are identical; the surface area of a sphere with radius r is equal to the areas of 4 circles with radius r.

\n" ); document.write( "Since in this problem the circles have radius 7, the sphere also has radius 7. \n" ); document.write( "

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