Saturday

April 19, 2014

April 19, 2014

Posted by **Jennifer** on Tuesday, May 21, 2013 at 5:42pm.

- pre calc -
**MathMate**, Tuesday, May 21, 2013 at 6:12pmIf sin(x)=-3/5 in Q3, then

cos(x)=-4/5 (using cos²(x)=1-sin²(x))

Similarly,

cos(y)=5/13 in Q1 means sin(y)=12/13

sin(x-y)=sin(x)cos(y)-cos(x)sin(y)

=-3/5*5/13 - (-4/5)*12/13

=(-15+48)/65

=33/65

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