document.write( "Question 562459: have an equilateral triangle with sides of 13 in. How do I find the area? I know formula is A=1/2bh. Base is 13 but what is height? \n" ); document.write( "

Algebra.Com's Answer #364599 by Edwin McCravy(20060) $\"\"$ $\"About$

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have an equilateral triangle with sides of 13 in. How do I find the area? I know formula is A=1/2bh. Base is 13 but what is height?
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document.write( "Draw it:\r\n" );
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document.write( "Draw the height (in green), which will divide the bottom\r\n" );
document.write( "13 in. bottom side into two 6.5 in. parts:\r\n" );
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document.write( "If we look at only the left half of the triangle, we\r\n" );
document.write( "see that it is a right triangle:\r\n" );
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document.write( "The Pythagorean theorem applies to right triangles\r\n" );
document.write( "and says that\r\n" );
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document.write( " 6.5² + h² = 13²\r\n" );
document.write( "42.25 + h² = 169  \r\n" );
document.write( "        h² = 126.75\r\n" );
document.write( "         h = \r\n" );
document.write( "         h = 11.25833025     \r\n" );
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document.write( "Now use the formula:\r\n" );
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document.write( "   A = bh\r\n" );
document.write( "   A = (6.5)(11.24833025)\r\n" );
document.write( "   A = 36.58957331 square inches\r\n" );
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document.write( "Edwin

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