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If sin A=4/5 and cos B=-12/13,where A and B lie in first and third quadrant respectively, thencos(A + B) = |
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Answer» Answer: Step-by-step explanation: 3,4,5 are Pythagoras triple sin A =4/5 COS A=adj/hyp=3/5 5,12,13 are Pythagoras triple cos B=12/13 sin B=opp/hyp=5/13 cos(A+B)=cos Acos B-sin ASIN B =(3/5×12/13)-(4/5×5/13) =36/65-4/13 =16/65 |
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