Can anyone tell me whether angle A is acute or obtuse.Thanks...and help me with the qn too...i got a different answer.
cscA = 5/3, where 90deg < A < 180deg
csc = hyp /opp
So A is in the 2nd quadrant.
The reference triangle of A has:
opposite side = 3
adjacent side = -4 ----------you know how to get this?
hypotenuse = 5
hence,
tanA = opp/adj = 3 /(-4) = -3/4
---
cosB = 5/13, where -90deg < B < 0deg
cos = adj /hyp
So, B is the 4th quadrant.
The reference right triangle of B has:
opp = -12 -----how about this?
adj = 5
hyp = 13
hence,
tanB = -12/5
Then,
tan(A +B)
= [tanA +tanB] / [ 1 -tanAtanB]
= [-3/4 -12/5] / [ 1 -(-3/4)(-12/5)]
= 63/16 ------------------------------answer.