document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=916121>Question 916121</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given cosA=1/3,A is quadrant IV and cosB=-squareroot7/4: B is in quadrant II find cos(A-B) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #555925 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=555925\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Given cosA=1/3,A is quadrant IV and cosB=-squareroot7/4: B is in quadrant II find cos(A-B)<BR>\n" );
document.write( "***<BR>\n" );
document.write( "sinA=-&#8730;(1-cos^2A)=-&#8730;(1-1/9)=-&#8730;(8/9)=-&#8730;8/3<BR>\n" );
document.write( "sinB=&#8730;(1-cos^2B)=&#8730;(1-7/16)=&#8730;(9/16)=3/4<BR>\n" );
document.write( "..<BR>\n" );
document.write( "cos(A-B)<BR>\n" );
document.write( "=cosAcosB+sinAsinB<BR>\n" );
document.write( "=1/3*-&#8730;7/4+(-&#8730;8/3)*3/4<BR>\n" );
document.write( "=-&#8730;7/12-3&#8730;8/12<BR>\n" );
document.write( "=-(&#8730;7+3&#8730;8)/12<BR>\n" );
document.write( "..<BR>\n" );
document.write( "Check:<BR>\n" );
document.write( "cosA=1/3<BR>\n" );
document.write( "A=289.47&#730;<BR>\n" );
document.write( "cosB=-&#8730;7/4<BR>\n" );
document.write( "B=131.41&#730;<BR>\n" );
document.write( "A-B=289.47-131.41=158.06<BR>\n" );
document.write( "cos(A-B)=cos(158.06&#730;)=-0.9276...<BR>\n" );
document.write( "as calculated:cos(A-B)=-(&#8730;7+3&#8730;8)/12=-0.9276... </SPAN>\n" );
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