SOLUTION: Find the exact value of the following given the conditions, I was able to find cos (A+B): {{{tanA= -7/24 }}} , {{{pi/2 < A < pi}}} ; {{{cosB= 5/6}}} {{{0 < B

SOLUTION: Find the exact value of the following given the conditions, I was able to find cos (A+B): {{{tanA= -7/24 }}} , {{{pi/2 < A < pi}}} ; {{{cosB= 5/6}}} {{{0 < B < pi/2}}} {{{sin(

Question 719842: Find the exact value of the following given the conditions, I was able to find cos (A+B):
, ;

Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!
I'm not sure how you can figure out cos(A-B) but not the others. You must have figured out sin(A), sin(B) and cos(A) to figure out cos(A-B). Just use these same values in the formulas:
sin(A+B) = sin(A)cos(B) + cos(A)sin(B)
and
sin(A-B) = sin(A)cos(B) - cos(A)sin(B)

So we will need tan(A) and tan(B) to find tan(A-B). We were given tan(A). Using the same triangles you used to figure out the sin's and cos's of A and B we should be able to find tan(B):

Now just use these values in the tan(A-B) formula.

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