In QII, we have
sinx = -5/13
tanx = -5/12
siny = -8/17
cosy = -15/17
cos(x-y) = cosx cosy + sinx siny
tan2x = 2tanx/(1 - tan^2 x)
Now plug in your numbers
if cosx=-12/13 and tany =8/15, pi/2<x<pi, pi<x<3pi/2 evaluate the following
a) cos(x-y) b)tan2x
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