\r\n" );
document.write( "
tells us that angle u is in\r\n" );
document.write( "the fourth quadrant. \r\n" );
document.write( "\r\n" );
document.write( "Since 
and we are given that\r\n" );
document.write( "
, we consider the 
as 
,\r\n" );
document.write( "the we can make the numerator be the adjacent side of +5 and \r\n" );
document.write( "the denominator be -1. \r\n" );
document.write( "\r\n" );
document.write( "So we draw a right triangle in the fourth quadrant whose adjacent\r\n" );
document.write( "side is +5 and whose opposite side is -1. [We knew to consider\r\n" );
document.write( "the -5 as and not 
because\r\n" );
document.write( "+5 goes to the right and -1 goes down.] \r\n" );
document.write( "\r\n" );
document.write( "The angle u is represented by the red arc drawn counterclockwise\r\n" );
document.write( "from the right side of the x-axis to the terminal side which is\r\n" );
document.write( "the hypotenuse of the right triangle.\r\n" );
document.write( "\r\n" );
document.write( "The hypotenuse is calculated from the Pythagorean theorem:\r\n" );
document.write( "
\r\n" );
document.write( "
\r\n" );
document.write( "
\r\n" );
document.write( "
\r\n" );
document.write( "
<-- the hypotenuse is always positive!\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "Now we use some double angle identities:\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "We could use the formula for tan(2u), but it's easier\r\n" );
document.write( "to use \r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" );
document.write( "![\"\"](\"/images/stars/stars-13.gif\")
