document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=431469>Question 431469</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Derive the half angle formula for sin( u/2 ) by following the steps below.<BR>\n" );
document.write( "(a) Use the sum angle formula to write cos(2x) in terms of powers of sin(x)<BR>\n" );
document.write( "and cos(x) .<BR>\n" );
document.write( "(b) Use a trig identity to rewrite cos(2x) in terms of just powers of sin(x):<BR>\n" );
document.write( "(c) Solve the formula in part (b) in terms of sin(x), and not a power of<BR>\n" );
document.write( "sin(x).<BR>\n" );
document.write( "(d) Substitute x = u/2 into the formula in part (c). </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #299459 by </B><A HREF=/tutors/aboutme.mpl?userid=richard1234><B>richard1234(7193)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richard1234><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=richard1234><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=299459\">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%282x%29+=+cos%5E2%28x%29+-+sin%5E2%28x%29+=+cos%5E2%28x%29+%2B+sin%5E2%28x%29+-+2sin%5E2%28x%29+=+1+-+2sin%5E2%28x%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%282x%29+-+1+=+-2sin%5E2%28x%29 ALIGN=MIDDLE  ALT=\"cos%282x%29+-+1+=+-2sin%5E2%28x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%5E2%28x%29+=+%281+-+cos%282x%29%29%2F2 ALIGN=MIDDLE  ALT=\"sin%5E2%28x%29+=+%281+-+cos%282x%29%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%28x%29+=+sqrt%28%281+-+cos%282x%29%29%2F2%29 ALIGN=MIDDLE  ALT=\"sin%28x%29+=+sqrt%28%281+-+cos%282x%29%29%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Replacing x with u/2,\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%28u%2F2%29+=+sqrt%28%281+-+cos%28u%29%29%2F2%29 ALIGN=MIDDLE  ALT=\"sin%28u%2F2%29+=+sqrt%28%281+-+cos%28u%29%29%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > (however you must be careful what quadrant u and u/2 are in, because it could be positive or negative). </SPAN>\n" );
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