cosx = -5/13 where pi/2 < x < pi find

a) sin2x

any idea how to do this?

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- Dec 10th 2008, 05:54 PMmike41cosx = -5/13 ... find sin2x
cosx = -5/13 where pi/2 < x < pi find

a) sin2x

any idea how to do this? - Dec 10th 2008, 06:06 PMskeeter
find the value of using the value they gave you for by sketching a reference triangle in quad II.

then use the double angle identity ...

- Dec 10th 2008, 06:24 PMmike41
wow thank you skeet

thought there was another way to solve it