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If A and B are two angles in standard position in Quadrant I, find cos(A + B) for the given function values.
sin A = 8/17 and cos B = 12/13

 Mar 13, 2020
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Q I      sin and cos are both positive

        Usung   cos^2 + sin ^2 = 1     you will find   cos a =  + 25/17       

                                                                                      and   sin b  =  + 5 /13

 

Now use this trig identity:

cos (a+b) =  cos a cos b - sin a sin b     for your answer.........   cheeky

 Mar 13, 2020

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