Question

find the value of tan (a-B) if cos a=3/5, sin B=5/13, 0 degrees< a <90degrees, and 0 degrees < B <90 degrees

Answer 1

@chlobohoe

Answer 2

tan(a-b) = (tana - tanb)/(1 + tanatanb)

a in Q2 : sina > 0
cosa = -3/5
sina = 4/5
tana = -4/3

b in Q2: sinb < 0
sinb = 5/13
cosb = -12/13
tanb = -5/12

tan(a-b) = (-4/3 + 5/12)/(1 + 20/36)
tan(a-b) = (-48+15)/(36 + 20) = -33/56

==Note: the correct solution is -33/56, not +33/56

Answer 3

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Answer 4

Thank you! <3