document.write( "Question 1109048: A sector of 120 degrees has a radius of 9 cm. The sector is then folded to form a cone. Find the exact value for the height \"h\" of the cone. Hence, find the volume.
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Algebra.Com's Answer #724069 by KMST(5328)\"\" \"About 
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\"120%5Eo%2F360%5Eo=1%2F3\"
\n" ); document.write( "The sector is \"1%2F3\" of the circle,
\n" ); document.write( "so its arc is \"1%2F3\" of the circumference of radius \"9cm\" .
\n" ); document.write( "When the sector is folded, that arc will be
\n" ); document.write( "the circumference of the base of the cone,
\n" ); document.write( "so that circumference will be \"1%2F3\" of the circumference of radius \"9cm\" ,
\n" ); document.write( "and its radius will be \"1%2F3\" of \"9cm\" ,
\n" ); document.write( "or \"r%5Bcone%5D=%281%2F3%29%289cm%29=3cm\" .
\n" ); document.write( "The slant height of the cone formed is the \"9cm\" radius of the sector.
\n" ); document.write( "A cross section of the cone passing through apex and center of the base will look like this
\n" ); document.write( " As per Pythagorean theorem, the exact value of the height is
\n" ); document.write( "\"h=sqrt%28%289cm%29%5E2-%283cm%29%5E2%29\"\"%22=%22\"\"sqrt%2872%29\"\"cm\"\"%22=%22\"\"6sqrt%282%29\"\"cm\" .
\n" ); document.write( "An approximate value is \"8.485cm\"
\n" ); document.write( "Then, the volume is
\n" ); document.write( "\"V%5Bcone%5D\"\"%22=%22\"\"%28pi%2F3%29h%2Ar%5E2\"\"%22=%22\"\"%28pi%2F3%296sqrt%282%293\"\"cm%5E3\"\"%22=%22\"\"18sqrt%282%29%2Api\"\"cm%5E3\" .
\n" ); document.write( "That is the exact expression for the volume.
\n" ); document.write( "\"79.97cm%5E3\" is an approximate value.
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