document.write( "Question 552045: in the accompanying diagram of Triangle ABC, AB is congruent to AC. The measure of Angle B is 40 degrees. What is the measure of Angle A? \n" ); document.write( "
Algebra.Com's Answer #360052 by AnlytcPhil(1806)\"\" \"About 
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document.write( "Since AB is congruent to AC, we know that ᐃABC is\r\n" );
document.write( "isosceles.  Therefore we know that its base angles are\r\n" );
document.write( "congruent and thus have the same measure.  Therefore we\r\n" );
document.write( "will label the measure of the other base angle C, m∠A = 40°\r\n" );
document.write( "as well:\r\n" );
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document.write( "Since we know that the sum of the measures of the three angles of any \r\n" );
document.write( "triangle must always equal to 180°, we can write\r\n" );
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document.write( "m∠A + m∠B + m∠C = 180°\r\n" );
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document.write( "m∠A + 40° + 40° = 180°\r\n" );
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document.write( "      m∠A + 80° = 180°\r\n" );
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document.write( "            m∠A = 180° - 80°\r\n" );
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document.write( "            m∠A = 100°\r\n" );
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document.write( "Edwin
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