posted by Riley on .
If sin(theta)=15/17 and cos(beta)=(-5/13 (both theta and beta are in quadrant II) find tan(theta+beta)
You should recognize the 8,15,17 and 5,12,13 right-angled triangles
so in II if
sinØ= 15/17, then cosØ = -8/17 and tanØ = - 15/8
cosß = -5/13 , then sinß = 12/13 and tanß = -12/5
tan(Ø+ß) = (tanØ + tanß)/(1 - tanØtanß)
you finish the arithmetic.
Ok i understand until you say that tan(theta) +tan(beta) needs to be divided by 1-tan(theta)tan(beta) where does that come from?
I assumed you knew the formulas, since you have know them to do these kind of problems
look under "other identities"
I do but why did u use that one. Im trying to understand because i have a test tomorrow and i have to do well on it.
well, it asked for tan(Ø+ß) didn't it?
The letters themselves of course don't matter
tan(A+B) =(tanA + tanB)/(1- tanAtanB)