document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1189035>Question 1189035</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given that X is an acute angle and COS X = (2√5)/5, find tan (90-x)Given that X is an acute angle and COS X = (2√5)/5, find tan (90-x) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #820261 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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/cgi-bin/show-face.mpl?user=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=820261\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Given that x is an acute angle and cos(x) = (2√5)/5, find tan (90-x)<BR>\n" );
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document.write( "cos(x) = sin(90-x) = 2sqrt(5)/5<BR>\n" );
document.write( "Call (90-x) y<BR>\n" );
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document.write( "sin(y) = 2sqrt(5)/5<BR>\n" );
document.write( "cos(y) = sqrt(1 - sin^2(y)) = sqrt(1 - 20/25) = sqrt(1/5) =sqrt(5)/5<BR>\n" );
document.write( "tan(y) = sin(y)/cos(y) = 2sqrt(5)/5)/(sqrt(5)/5) = 2<BR>\n" );
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