document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1036929>Question 1036929</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Question#1:<BR>\n" );
document.write( "Find the exact value of each of the following. (Hint: you may need Angle Sum/Difference, Double Angle, or Half Angle Identities):\r<BR>\n" );
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document.write( "a. cos(13pi/12)\r<BR>\n" );
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document.write( "b. sin(pi/8)\r<BR>\n" );
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document.write( "c. tan(2X) if cosX = 5/6 and X is in Quadrant 1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #651639 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=651639\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the exact value of each of the following. (Hint: you may need Angle Sum/Difference, Double Angle, or Half Angle Identities): <BR>\n" );
document.write( "a. cos(13pi/12) = cos[(3pi/4 + (pi/3)] = cos(3pi/4)cos(pi/3)-sin(3pi/4)sin(pi/3)<BR>\n" );
document.write( "= (-sqrt(2)/2)(1/2)) - (sqrt(2)/2)(sqrt(3)/2)<BR>\n" );
document.write( "etc.<BR>\n" );
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document.write( "b. sin(pi/8) = sin[(pi/4)/2] = sqrt[(1-cos(pi/4))/2] = sqrt[1-(sqrt(2)/2))/2]<BR>\n" );
document.write( "= sqrt[(2-sqrt(2))/4] = sqrt[(1/2) - sqrt(2)/4] \r<BR>\n" );
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document.write( "c. tan(2t) if cos(t) = 5/6 and t is in Quadrant 1<BR>\n" );
document.write( "cos = x/r, so   x= 5 and r = 6<BR>\n" );
document.write( "then y = sqrt[6^2-5^2] = sqrt(11)<BR>\n" );
document.write( "Therefore tan(t) = y/x = sqrt(11)/5<BR>\n" );
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document.write( "tan(2t) = sqrt[2tan(t)/(1-tan^2(t)] = sqrt[(2sqrt(11)/5)/(1-(11/25))]<BR>\n" );
document.write( "etc.<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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