Question 719842
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)<br>
{{{tan(A-B) = (tan(A)-tan(B))/(1+tan(A)tan(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):
{{{tan(B) = sqrt(11)/5}}}
Now just use these values in the tan(A-B) formula.