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Find the exact value of the trigonometric function given that sin u = 5/13 and cos v = -3/5 (Both are in Quadrant II.) sin (u + v)
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I am going to use the formula
sin(u+v) = sin(u)*cos(v) + cos(u)*sin(v). (*)
For it, in addition to the given values sin(u) = 5/13 and cos(v) = -3/5 I need to know cos(u) and sin(v).
1. cos(u) = = = = = = .
The sign "-" is at the sqrt since cosine is negative in QII.
2. sin(v) = = = = = .
The sign "+" is at the sqrt since sine is positive in QII.
3. Now you have everything to use the formula (*). Substitute all given and found values into (*). You will get
sin(u+v) = sin(u)*cos(v) + cos(u)*sin(v) = = = .
Answer. sin(u+v) = .