Has a negative -5/13
Steve. If angles x and y are in the same quadrant and sin x =3/5 and cos y= -5/13 determine the value of sin (x-y)
well, that does make a difference.
You just need to think about what happens in the various quadrants. Recall that
sinθ = y/r
cosθ = x/r
r is always positive, so if sinx is positive, and cosy is negative, that means you are in QII.
Now you know that
sinx = 3/5
cosx = -4/5
siny = 12/13
cosy = -5/13
Now just crank it out.
Don't be afraid to use what you know. At this point, that is not a lot, so the problems can't be too complicated. Just sit back, take a breath, and review the relevant section in your text.