document.write( "Question 679728: If you have an equilateral triangle and the sides are 10, then what is the altitude? \n" ); document.write( "

Algebra.Com's Answer #422043 by Edwin McCravy(20059) $\"\"$ $\"About$

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document.write( "Draw the altitude (in green, labeled \"a\") which splits the equilateral triangle\r\n" );
document.write( "into two congruent right triangles, and splits the bottom 10-unit \r\n" );
document.write( "side of the equilateral triangle into two parts, each 5 units long:\r\n" );
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document.write( "Now we look at just the left right triangle:\r\n" );
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document.write( "We use the Pythagorean theorem, where c is the hypotenuse, the\r\n" );
document.write( "side which is 10 units long, a = the (green) altitude, and b =\r\n" );
document.write( "the base, or bottom side of the right triangle, which is 5 units\r\n" );
document.write( "long:\r\n" );
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document.write( " c² = a² + b²\r\n" );
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document.write( "10² = a² + 5²\r\n" );
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document.write( "100 = a² + 25\r\n" );
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document.write( " 75 = a²\r\n" );
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document.write( "V75 = a\r\n" );
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document.write( "V25·3 = a\r\n" );
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document.write( "5V3 = a\r\n" );
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document.write( "So the altitude \"a\", is about 8.66 units long.\r\n" );
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document.write( "Edwin

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