document.write( "Question 315355: The centers of two circles with radii of 3 and 5 are 17 units apart. Find the length of the common internal tangent. Answer either in exact form or rounded to the nearest tenth.\r
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Algebra.Com's Answer #225671 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Given AC=3, BD=5, AB=17\r\n" );
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document.write( "Need to find internal tangent CD\r\n" );
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document.write( "Extend radius AC by 5 units to E, where CE is 5 units long.\r\n" );
document.write( "then Draw BE, so that CDBE is a rectangle.\r\n" );
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document.write( "Now triangle ABE is a right triangle, with shorter leg AE = 3+5 = 8,\r\n" );
document.write( "and hypotenuse AB which is given to be 17.\r\n" );
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document.write( "So by the Pythagorean theorem,\r\n" );
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document.write( "\"AE%5E2%2BEB%5E2=AB%5E2\"\r\n" );
document.write( "\"8%5E2%2BEB%5E2=17%5E2\"\r\n" );
document.write( "\"64%2BEB%5E2=289\"\r\n" );
document.write( "\"EB%5E2=225\"\r\n" );
document.write( "\"EB=sqrt%28225%29\"\r\n" );
document.write( "\"EB=15\"\r\n" );
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document.write( "And since CDBE is a rectangle, CD = EB = 15\r\n" );
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document.write( "So the internal tangent, CD, is 15 units.\r\n" );
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document.write( "Edwin
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