SOLUTION: Hello I need help with given sinA= 4/5 cosB= 5/13 both A and B in quadrant I, find tan(A+B)

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Question 916108: Hello I need help with given sinA= 4/5 cosB= 5/13 both A and B in quadrant I, find tan(A+B)
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!

sinA= 4/5
sin^2A=16/25
1-cos^2A=16/25
cos^2A=9/25
cos A = 3/5
sin A / cos A = (4/5) / (3/5)
tan A = 4/3


cosB= 5/13
tan B = 12/5
tan(A + B) = [ tan A + tan B ] / [ 1 - tan A tan B]
= (4/3 + 12/5) /(1-(4/3)(12/5))
=(56/15)/(-33/15)
=-56/33