Question 1089349
use a sketch to find exact value of the expression. 
cos(tan^-1 5/4)
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tan = y/x = 5/4
r = sqrt(x^2 + y^2) = sqrt(41)
cos = x/r = 4/sqrt(41)
= 4sqrt(41)/41
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Could be + or minus.  The quadrant wasn't given.