Question 1197232
If sec x= 3/2 and cosec y= 3; determine cos (x+y)
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sec = 3/2 ---> cos(x) = 2/3
{{{sin(x) = sqrt(1 -cos^2(x)) = sqrt(5)/3}}}
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csc = 3 ----> sin(y) = 1/3
{{{cos(y) = sqrt(1 - sin^2(y)) = sqrt(8/9) = 2sqrt(2)/3}}}
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cos(x+y) = cos(x)*cos(y) - sin(x)*sin(y)  ------  I'm pretty sure.
Look it up at "half-angle formulas" on Wikipedia.