document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=155226>Question 155226</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/032113186x/algebrahomeworkh>precalculus</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> prove (we have to work with the left side)\r<BR>\n" );
document.write( "\n" );
document.write( "cos(2u)=cos^2u </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #114288 by </B><A HREF=/tutors/aboutme.mpl?userid=jojo14344><B>jojo14344(1513)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jojo14344><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=114288\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%282u%29=cos%5E2%28u%29 ALIGN=MIDDLE  ALT=\"cos%282u%29=cos%5E2%28u%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "By double -Angle Formula:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%282u%29=2cos%5E2%28u%29-1 ALIGN=MIDDLE  ALT=\"cos%282u%29=2cos%5E2%28u%29-1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "So,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2cos%5E2%28u%29-1=cos%5E2%28u%29 ALIGN=MIDDLE  ALT=\"2cos%5E2%28u%29-1=cos%5E2%28u%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2cos%5E2%28u%29-cos%5E2%28u%29=1 ALIGN=MIDDLE  ALT=\"2cos%5E2%28u%29-cos%5E2%28u%29=1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29%282-1%29=1 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29%282-1%29=1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29=1 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29=1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29-1=0 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29-1=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "By Pythagorean Identities:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%5E2%28u%29%2Bcos%5E2%28u%29=1 ALIGN=MIDDLE  ALT=\"sin%5E2%28u%29%2Bcos%5E2%28u%29=1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%5E2%28u%29=1-cos%5E2%28u%29 ALIGN=MIDDLE  ALT=\"sin%5E2%28u%29=1-cos%5E2%28u%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Therefore,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29-1 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29-1\"   DISABLED_style= \"max-width:90%; height:auto;\" > -----------> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-sin%5E2%28u%29 ALIGN=MIDDLE  ALT=\"-sin%5E2%28u%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Thank you,<BR>\n" );
document.write( "Jojo </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );