document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=18605>Question 18605</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am terrible with algebraic manipulations.  I need to solve the following equation for L.  I do not want the answer to the question as I have the answer already from the back of the book - I simply need help in rearranging the formula to solve for L.  I have the values for P2/P1, and X (I even have the value for L from the solution manual) I know I need to move cos to the other side and I should be solving for cos^-1; however, I am missing some \"gene\" that does not allow me to figure it out correctly.  Any help you can give me would be greatly appreciated.\r<BR>\n" );
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document.write( "P2/P1 = cos^2 [(pi*L) / (2X) ] </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #8912 by </B><A HREF=/tutors/aboutme.mpl?userid=mmm4444bot><B>mmm4444bot(95)</B></A><img src=\"/images/stars/stars-08.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mmm4444bot><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=8912\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hello There:\r<BR>\n" );
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document.write( "I'll take a stab at it.\r<BR>\n" );
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document.write( "P2/P1 = cos[(L*pi)/(2*X)]^2\r<BR>\n" );
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document.write( "Take the square root of both sides.\r<BR>\n" );
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document.write( "cos[(L*pi)/(2*X)] = +/- sqrt(P2/P1)\r<BR>\n" );
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document.write( "Use the inverse cosine function (arccos) to get L out of the input to cosine.\r<BR>\n" );
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document.write( "arccos[+/- sqrt(P2/P1)] = L*pi/(2*X)\r<BR>\n" );
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document.write( "Multiply both sides by (2*X)/pi.\r<BR>\n" );
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document.write( "L = [(2*X)/pi]*arccos[+/- sqrt(P2/P1)]\r<BR>\n" );
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document.write( "Hopefully, this matches the result in your book.  You need to decide what to do about the +/- part.  In other words, maybe only the positive one is applicable.\r<BR>\n" );
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document.write( "~ Mark<BR>\n" );
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