document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=148791>Question 148791</A>: <I><SPAN STYLE=\"word-break: break-all;\"> when you first walk into weaver there are 2 large regular octogonal pillars. the edges are 6.5 and they are 9 feet tall. how much granite was needed to build these pillars?? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #109159 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=109159\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> To solve this problem, you need to know the volume of each pillar.  The volume is \"area of the base\" times \"height\".<BR>\n" );
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document.write( "\"area of the base\" = \"area of an octagon\"<BR>\n" );
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document.write( "Without trying to derive the formula of an octagon, I'll just use it.  But, for reference, you might want to check out:<BR>\n" );
document.write( "http://www.mathreference.com/geo,hex.html<BR>\n" );
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document.write( "\"area of an octagon\" = 2(1+sqrt(2))S^2<BR>\n" );
document.write( "where S=length of one edge<BR>\n" );
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document.write( "So, plugging in your numbers to:<BR>\n" );
document.write( "\"area of an octagon\" = 2(1+sqrt(2))S^2<BR>\n" );
document.write( "\"area of an octagon\" = 2(1+sqrt(2))6.5^2<BR>\n" );
document.write( "\"area of an octagon\" = 2(1+sqrt(2))42.45<BR>\n" );
document.write( "\"area of an octagon\" = 2(1+1.414)42.45<BR>\n" );
document.write( "\"area of an octagon\" = 2(2.414)42.45<BR>\n" );
document.write( "\"area of an octagon\" = (4.828)42.45<BR>\n" );
document.write( "\"area of an octagon\" = 204 sq ft<BR>\n" );
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document.write( "Now, to get the volume we multiply the area times the height:<BR>\n" );
document.write( "\"vol of one pillar\" = \"area of an octagon\" * \"height of pillar\"<BR>\n" );
document.write( "\"vol of one pillar\" = 204 * 9<BR>\n" );
document.write( "\"vol of one pillar\" = 1836 cubic feet<BR>\n" );
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document.write( "Since we have 2 pillars, we multiply the above by 2:<BR>\n" );
document.write( "2 * 1836 = 3672 cubic feet<BR>\n" );
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document.write( "That's how much granite you need.\r<BR>\n" );
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