cosx = -5/13 where pi/2 < x < pi find a) sin2x any idea how to do this?
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find the value of $\displaystyle \sin{x}$ using the value they gave you for $\displaystyle \cos{x}$ by sketching a reference triangle in quad II. then use the double angle identity ... $\displaystyle 2\sin{x} \cos{x} = \sin(2x)$
wow thank you skeet thought there was another way to solve it
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