document.write( "Question 939227: The triangle is isosceles and the perimeter equals 54 cm. The height is 3*sqrt(21). Find the lengths of the sides and the area of the triangle. Express your answers in simplest radical form. \n" ); document.write( "
Algebra.Com's Answer #572290 by TimothyLamb(4379)\"\" \"About 
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definition of isosceles triangle: a triangle with two equal sides
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\n" ); document.write( "the problem doesn't say which height is being talked about, so let's assume it's the height from the non-equal side (the base b), to the point where the two equal sides meet:
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\n" ); document.write( "perimeter = 54 = 2s + b
\n" ); document.write( "2s = 54 - b
\n" ); document.write( "s = (54 - b)/2
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\n" ); document.write( "length of the equal sides:
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\n" ); document.write( "s = sqrt( hh + bb/4 )
\n" ); document.write( "(54 - b)/2 = sqrt( hh + bb/4 )
\n" ); document.write( "(54 - b)(54 - b)/4 = hh + bb/4
\n" ); document.write( "54*54 - 108b + bb = 4hh + bb
\n" ); document.write( "2916 - 108b = 4hh
\n" ); document.write( "108b = 2916 - 4hh
\n" ); document.write( "b = (2916 - 4hh)/108
\n" ); document.write( "b = (2916 - 4* 3*sqrt(21) * 3*sqrt(21) )/108
\n" ); document.write( "b = (2916 - 4*3*3*sqrt(21)*sqrt(21) )/108
\n" ); document.write( "b = (2916 - 4*3*3*21 )/108
\n" ); document.write( "b = 20 cm
\n" ); document.write( "s = (54 - b)/2
\n" ); document.write( "s = (54 - 20)/2
\n" ); document.write( "s = 17 cm
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\n" ); document.write( "area:
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\n" ); document.write( "a = bh/2
\n" ); document.write( "a = 20*3*sqrt(21)/2
\n" ); document.write( "a = 30*sqrt(21) sq.cm
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