document.write( "Question 295419: given: Secants ADB and CEB intersect at B.
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Algebra.Com's Answer #213540 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "I'll just explain how to prove it.  You can write up a\r\n" );
document.write( "two-line proof of it.\r\n" );
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document.write( "Let O be the center of the circle.  Draw in four radii, OA, OC, OD, OE.\r\n" );
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document.write( "Triangle AOD is congruent to triangle COE by SSS since AD and CE are\r\n" );
document.write( "given congruent and the other sides are radii of the same circle.\r\n" );
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document.write( "Therefore angles DAO and ECO are congruent by CPCT.\r\n" );
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document.write( "Triangle AOC is isosceles because it has two sides OA and OC which are both\r\n" );
document.write( "radii of the same circle and are congruent.\r\n" );
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document.write( "Therefore angles OAC and OCA are congruent because they are\r\n" );
document.write( "the base angles of isosceles triangle AOC.\r\n" );
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document.write( "Angles DAC and ECA are congruent because they are, respectively,\r\n" );
document.write( "the sums of angles DAO+OAC and ECO+OCA.\r\n" );
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document.write( "Therefore Triangle ABC is isosceles since its base angles DAC and\r\n" );
document.write( "ECA are congruent.\r\n" );
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document.write( "Edwin
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