document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=62060>Question 62060</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am a grade 10 student and we have read abt multiple and sub multiple angles..<BR>\n" );
document.write( "I have problem with this questions..I hope that my question will be answered\r<BR>\n" );
document.write( "\n" );
document.write( "prove that:<BR>\n" );
document.write( "sin6.sin42.sin66.sin78=(1/16) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #42824 by </B><A HREF=/tutors/aboutme.mpl?userid=venugopalramana><B>venugopalramana(3286)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=venugopalramana><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.geocities.com/venugopalramana/FREE_MATHS_ASSISTANCE.html valign=middle><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=42824\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I am a grade 10 student and we have read abt multiple and sub multiple angles..<BR>\n" );
document.write( "I have problem with this questions..I hope that my question will be answered <BR>\n" );
document.write( "prove that:<BR>\n" );
document.write( "sin6.sin42.sin66.sin78=(1/16)<BR>\n" );
document.write( "tpt 4sin6*sin48*sin66*sin78=1/4<BR>\n" );
document.write( "lhs = (2si6sin66)(2sin42sin78)=[cos60-cos72][cos36-cos120]<BR>\n" );
document.write( "=[0.5-cos72][0.5+cos36]<BR>\n" );
document.write( "here we have to use the stndard expansions for cos72&cos36<BR>\n" );
document.write( "cos72=[sqrt(5)-1]/4.....cos36=[sqrt(5)+1]/4<BR>\n" );
document.write( "lhs=0.25+0.5[{sqrt(5)+1}/4-{sqrt(5)-1}/4] - [{sqrt(5)+1}/4][{sqrt(5)-1}/4]<BR>\n" );
document.write( "=0.25+0.5*0.5-0.25=0.25=/4=rhs </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );