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document.write( "Begin by drawing an isosceles triangle ABC:\r\n" );
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document.write( "Now I'll draw a green line AD, from the top vertex A to the bottom side BC, but\r\n" );
document.write( "not perpendicular to BC, meeting BC at D, like this:\r\n" );
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\r\n" );
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document.write( "The two sides AB, AC, of the big isosceles triangle are congruent. The green\r\n" );
document.write( "line AD is congruent to itself. The base angles B and C of the big isosceles\r\n" );
document.write( "triangle ABC are congruent.\r\n" );
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document.write( "Therefore we have a case of SSA with triangles ABD and ACD. That is, two sides\r\n" );
document.write( "and a nonincluded angle of one triangle, ABD, are congruent to the\r\n" );
document.write( "corresponding two sides and angle of a second triangle ACD. However they are\r\n" );
document.write( "not congruent since AD is not perpendicular to the base BC. Therefore the two\r\n" );
document.write( "angles at D are supplementary but not congruent. \r\n" );
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document.write( "------------------------------------------------------------------\r\n" );
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document.write( "However, the following version of the SSA theorem can be proved:\r\n" );
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document.write( "SSA Theorem: If two sides and a nonincluded angle of one triangle are\r\n" );
document.write( "congruent to the corresponding two sides and angle of a second triangle, then\r\n" );
document.write( "the triangles are either congruent or else the angles opposite the congruent\r\n" );
document.write( "sides are supplementary. \r\n" );
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document.write( "Edwin
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document.write( "![\"\"](\"/images/stars/stars-13.gif\")
