document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=810781>Question 810781</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find sin (2 theta)<BR>\n" );
document.write( "Given: csc theta = 9/7, theta is in quadrant 2 </SPAN>\n" );
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document.write( "Given: csc theta = 9/7, theta is in quadrant 2<BR>\n" );
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document.write( "y is positive in QII ; x is negative in QII<BR>\n" );
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document.write( "csc = r/y = 9/7 implies that r = 9 and y = 7<BR>\n" );
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document.write( "Then x = -sqrt[9^2+7^2] = -sqrt(130)<BR>\n" );
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document.write( "cos(t) = x/r = -sqrt(130)/9<BR>\n" );
document.write( "sin(t) = y/r = 7/9<BR>\n" );
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document.write( "Your Problem:<BR>\n" );
document.write( "sin(2 t) = 2*sin(t)*cos(t) = 2*(7/9)(-sqrt(130)/9 = -14sqrt(130)/81<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "================== </SPAN>\n" );
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