# Find the exact value of the trigonometric function

Find the exact value of $$\cot(v-u)$$ given that $\sin u=−3/5$ and $\cos v = − 7/25$ (Both $u$ and $v$ are in Quadrant III.)

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Please don't just dump problems here --- tell us why you are interested in the question, what you know about it, where you get stuck in solving it, and so on. –  Gerry Myerson Oct 29 '12 at 2:13
Exact value of which trig function? –  André Nicolas Oct 29 '12 at 2:15
trig function of cot( v-u) –  MOG Oct 29 '12 at 2:19

Do you know formulas relating $\sin(A+B)$ and $\cos(A+B)$ to $\sin A,\sin B,\cos A, \cos B$?
Do you know a formula relating $\sin C$ and $\cos C$?