document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1171885>Question 1171885</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 10. find the exact value of the following by using the specified method.<BR>\n" );
document.write( "a. sin 157.5 degrees by using a half-angle identity<BR>\n" );
document.write( "b. cos 7pi/12 by using a sum identity </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #797354 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=797354\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sin (315/2)<BR>\n" );
document.write( "sin (x/2)=+/-sqrt((1-cos x)/2); cosine is positive in 4th quadrant and sine is positive in the second quadrant.<BR>\n" );
document.write( "=sqrt((1-cos 315)/2)<BR>\n" );
document.write( "= sqrt (1- sqrt(2)/2)/2<BR>\n" );
document.write( "= sqrt [(2-sqrt(2)/4)<BR>\n" );
document.write( "=(1/2)(sqrt (2- sqrt(2)) <BR>\n" );
document.write( "-<BR>\n" );
document.write( "cos 7π/12=cos (4π/12+3π/12)<BR>\n" );
document.write( "this is cos π/3*cosπ/4-sin π/3*sin π/4<BR>\n" );
document.write( "=(1/2)*sqrt(2)/2)-sqrt(3)/2*sqrt(2)/2<BR>\n" );
document.write( "=(1/2-sqrt(3/2))*sqrt(2)/2<BR>\n" );
document.write( "=(1-sqrt(3))/2*sqrt(2)/2<BR>\n" );
document.write( "=sqrt(2)/4-sqrt(6)/4 or (1/4)*(sqrt(2)-sqrt(6))<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );