SOLUTION: im completely lost on how to work these out, Given cos A =0.42 and sin B = 0.73 evaluate (a) sin(A - B) (b) cos(A

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Question 616888: im completely lost on how to work these out,
Given cos A =0.42 and sin B = 0.73 evaluate
(a) sin(A - B)
(b) cos(A - B)
(c) tan(A+B)
to 4 decimal places
Answer by jsmallt9(3758) (Show Source):
You can put this solution on YOUR website!
In order to solve these problems, we will need to be able to figure out what cos(B) and sin(A) are.

We're told that cos(A) = 0.42. Cos is positive in both the 1st and 4th quadrants. sin(A) will be positive if A terminates in the 1st quadrant but it will be negative if A terminates in the 4th.

Similarly, we cannot figure out the sign of cos(B) without knowing where B terminates.

So without information that could be used to determine the quadrants for A and B, these problems cannot be done. Either you or your teacher have left out something important.

SOLUTION: im completely lost on how to work these out, Given cos A =0.42 and sin B = 0.73 evaluate (a) sin(A - B) (b) cos(A - B) (c) tan(A+B) to 4 decimal places