SOLUTION: If cosA=12/13 and sineB=-1/2 with A and B in the fourth quadrant find cos(A-B) and tan(A+B)

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Question 1041484: If cosA=12/13 and sineB=-1/2 with A and B in the fourth quadrant find cos(A-B) and tan(A+B)
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
cos%5E2%28A%29%2Bsin%5E2%28A%29=1
%2812%2F13%29%5E2%2Bsin%5E2%28A%29=1
sin%5E2%28A%29=%28169-144%29%2F13%5E2
sin%5E2%28A%29=%285%2F13%29%5E2
Since it's Q4, sin%28A%29%3C0,
sin%28A%29=-5%2F13
and
similarly,
cos%5E2%28B%29%2Bsin%5E2%28B%29=1
cos%5E2%28B%29%2B%28-1%2F2%29%5E2=1
cos%5E2%28B%29=1-1%2F4
cos%5E2%28A%29=%283%2F4%29
Since it's Q4, cos%28A%29%3E0,
cos%28A%29=sqrt%283%29%2F2
So then,
cos%28A-B%29=cos%28A%29cos%28B%29%2Bsin%28A%29sin%28B%29
and
tan%28A%2BB%29=%28tan%28A%29%2Btan%28B%29%29%2F%281-tan%28A%29%2Atan%28B%29%29
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Fill in with the calculated values to complete the problem.