SOLUTION: Given: A and B are in quadrant 4, cos A=(15/17) and tan B=-(5/12); How do I find out sin(A+B) and cos(A+B)?

Question 872313: Given: A and B are in quadrant 4, cos A=(15/17) and tan B=-(5/12); How do I find out sin(A+B) and cos(A+B)?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
tan B=-(5/12)
tan^2B= 25/144
Sec^2B-1=25/144
cos^2B= 144/25
cos B = 12/5
cos A=(15/17)
cos^2A- 225/289
1-sin^2A= 225/289
1-225/289 = sin^2A
64/289 = sin^2A
-8/17 = sinA ( IV quadrant)
Sin (A+B) = = sinacosb + cosasinb

just plug in the values
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