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anonymous
 5 years ago
If both x and y are in quadrant IV, and sin x = 2/3 and cos y = 1/4. Find cos (xy)
anonymous
 5 years ago
If both x and y are in quadrant IV, and sin x = 2/3 and cos y = 1/4. Find cos (xy)

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0cos( xy)= cos x cosy+ sinx siny

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0sin x= 2/3 cox x =sqrt(1 +4/9)=sqrt(13)/3

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0cosx = sqrt(14/9)= sqrt(5)/3

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0cosy =1/4 siny = sqrt(11/16)=sqrt(15)/4

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0put the values in formula

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok thanks....another questions is to find sin (x+y) with the same variables... can you help me get started on that one also?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0oops, once would have been enough

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0sin(x+y)= sinxcosycosxsiny

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so for cos (xy) would it be: (√5/3)(1/4)+(2/3)(√15/4)=(√5/12)+(2√15/12)= √52√15/12

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0siny is negative in fourth quadrant sin y =sqrt(15)/4

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok so it would be √5+2√15/12

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0for sin (x+y) would it be (2/3)(1/4)(√5/3)((√15/4)= 2/12√75/12=25√3/12 are my negatives and positives right?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0u again missed that siny is negative

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0for sin (x+y) would it be (2/3)(1/4)(√5/3)((√15/4)= 2/12√75/12=25√3/12 are my negatives and positives right?
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