Question 923637
Suppose sin x = 1/7 cos x > 0,
Note: cos(x) = sqrt(49-1)/7 = sqrt(48)/7
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sin y = &#8722;2/5 and cos y < 0.
Note: cos(y) = -sqrt(25-4)/5 = -sqrt(21)/5
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Then 
cos x = 4sqrt(3)/7
cos y = -sqrt(21)/5
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Find each of the following quantities: 
sin(x + y) = sin(x)cos(y)+cos(x)sin(y)
Substitute to get the numerical answer.
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cos(x + y) = cos(x)cos(y)-sin(x)sin(y)
Substitute:: 
tan(x + y) =
Divide sin(x+y) by cos(x+y)
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Cheers,
Stan H.
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