SOLUTION: Hello, Guys I have 4 questions which I have no clue because I am having a hard time with quadrants. Find sin(a-b) if sin(a)=5/13 where a is in the second quadrant and cos(b)=-7/

Question 1031031: Hello, Guys I have 4 questions which I have no clue because I am having a hard time with quadrants.
Find sin(a-b) if sin(a)=5/13 where a is in the second quadrant and cos(b)=-7/25 where b is in the third quadrant.
-Find cos(a+b) if sin(a)=-8/17 where a is in the fourth quadrant and tan(b)=-20/21 where b is in the second quadrant.
-Find sin(a+b) if tan(a)=7/24 where a is in the third quadrant and cos(b)=-12/13 where b is in the second quadrant.
-Suppose that sin(t) = 3/5 and t is in the second quadrant. Evaluate cos(t+t) to 2 decimal places.
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
sin(a-b) = sin a cos b - cos a sin b
if sin(a)=5/13 where a is in the second quadrant cos a = 12/13 and cos is negative
and cos(b)=-7/25 where b is in the third quadrant. sin B = 24/25 and negative

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