document.write( "Question 189634: Equation of a Circle
\n" ); document.write( "7. The point (a, 8) lies on the circle defined by x^2+y^2=100.
\n" ); document.write( "a) Explain why there are two possible values for a. Find these values.
\n" ); document.write( "b) Use a graph to check that the points corresponding to both values for a are on the circle.
\n" ); document.write( "Thank you very much!!!! \n" ); document.write( "
Algebra.Com's Answer #142307 by Edwin McCravy(20060)\"\" \"About 
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Equation of a Circle
\n" ); document.write( "7. The point (a, 8) lies on the circle defined by x^2+y^2=100.
\n" ); document.write( "a) Explain why there are two possible values for a.
\n" ); document.write( "Find these values.
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document.write( "Here is why there are two possible values:\r\n" );
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document.write( "When you substitute x=a and y=8 into\r\n" );
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document.write( "\"x%5E2%2By%5E2=100\"\r\n" );
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document.write( "you get\r\n" );
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document.write( "\"a%5E2%2B8%5E2=100\"\r\n" );
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document.write( "Then you simplify and solve for \"a%5E2\".\r\n" );
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document.write( "\"a%5E2%2B64=100\"\r\n" );
document.write( "\"a%5E2=100-64\"\r\n" );
document.write( "\"a%5E2=36\"\r\n" );
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document.write( "But then when you take the square root, there\r\n" );
document.write( "are two square roots of 36, and so you get:\r\n" );
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document.write( "\"a=%22+%22%2B-sqrt%2836%29\"\r\n" );
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document.write( "which means these two answer:\r\n" );
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document.write( "\"a=6\" and \"a+=+-6\"\r\n" );
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\n" ); document.write( "b) Use a graph to check that the points corresponding to both values for a are on the circle.
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document.write( "You can see that both points (-6,8) and (6,8) are on\r\n" );
document.write( "the circle \"x%5E2%2By%5E2=100\"\r\n" );
document.write( "Edwin
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