document.write( "Question 209023This question is from textbook Geoemetry
\n" ); document.write( ": Prove: If an isosceles triangle has an altitude from the vertex to the base, then the altitude bisects the vertex angle.\r
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Algebra.Com's Answer #158013 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Given: Triangle ABC is isosceles; \r\n" );
document.write( "       Line segment CD is the altitude to the base AB\r\n" );
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document.write( "To prove: Angle ACD = angle BCD\r\n" );
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document.write( "angle A = angle B       Base angles of isosceles triangle\r\n" );
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document.write( "angle ADC = 90°         An altitude of a triangle is \r\n" );
document.write( "                        perpendicular to a side\r\n" );
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document.write( "angle BDC = 90°         An altitude of a triangle is \r\n" );
document.write( "                        perpendicular to a side\r\n" );
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document.write( "angle ADC = angle BDC   Both are right angles \r\n" );
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document.write( "Angle ACD = angle BCD   If two angles of one triangle are\r\n" );
document.write( "                        equal to two angles of another\r\n" );
document.write( "                        triangle, the third angles are \r\n" );
document.write( "                        equal.\r\n" );
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document.write( " Edwin
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