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# help

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If x is acute and tan x = 5, then find cos x.

Jun 14, 2020

So let x equal of one of the acute angles in a 90 degree triangle. Since $$tan=\frac {opposite}{adjacent}= \frac {5}{1}$$, and by the Pythagorean Identity, we can find that the sides are 5,1, and $$\sqrt 26$$. Therefore, cos x = $$\frac{adjacent}{hypotenuse}$$$$\frac{1}{\sqrt 26}$$ = $$\frac{\sqrt 26}{26}$$.