Find the exact value of the trigonometric function

Question

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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Gerry Myerson · Answer 1 · 2012-10-29 02:24:10Z

Some hints:

Do you know a formula relating the cotangent to the sine and cosine?

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 $\cos C$?

Do you know which trig functions are positive in which quadrants?

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