document.write( "Question 1042108: In △XY Z, it is given that XY = YZ and that ∠Y = 42°
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Algebra.Com's Answer #657046 by Edwin McCravy(20063) $\"\"$ $\"About$

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In △XY Z, it is given that XY = YZ and that ∠Y = 42°
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document.write( "Since XY = YZ, we know that ΔXYZ is isosceles and we have\r\n" );
document.write( "proved that the base angles of an isosceles triangle are\r\n" );
document.write( "equal.  So ∠X = ∠Z\r\n" );
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document.write( "We have also proved that the sum of the three interior angles of \r\n" );
document.write( "any triangle is 180°.\r\n" );
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document.write( "Therefore ∠X + ∠Y + ∠Z = 180°, and since ∠X = ∠Z,\r\n" );
document.write( "we can substitute ∠X for ∠Z, and also 42° for ∠Y and get:\r\n" );
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document.write( "          ∠X + 42° + ∠X = 180°\r\n" );
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document.write( "              2∠X + 42° = 180°\r\n" );
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document.write( "Subtract 42° from both sides gives:\r\n" );
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document.write( "                    2∠X = 138°\r\n" );
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document.write( "Dividing both sides by 2\r\n" );
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document.write( "                     ∠X = 69°\r\n" );
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document.write( "Edwin

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