Answer: [tex]\cos(\theta) = \frac{8\sqrt{113}}{113}\\\\[/tex]
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Work Shown:
x^2+y^2 = r^2
(8)^2+(-7)^2 = r^2
113 = r^2
r = sqrt(113)
The distance from (0,0) to (8,-7) is exactly sqrt(113) units.
This is the exact length of the hypotenuse of the right triangle.
Next, we do the following steps:
[tex]\cos(\text{angle}) = \frac{\text{adjacent}}{\text{hypotenuse}}\\\\\cos(\theta) = \frac{x}{r}\\\\\cos(\theta) = \frac{8}{\sqrt{113}}\\\\\cos(\theta) = \frac{8\sqrt{113}}{\sqrt{113}*\sqrt{113}}\\\\\cos(\theta) = \frac{8\sqrt{113}}{\sqrt{113*113}}\\\\\cos(\theta) = \frac{8\sqrt{113}}{\sqrt{113^2}}\\\\\cos(\theta) = \frac{8\sqrt{113}}{113}\\\\[/tex]
Side note: cosine is positive in quadrant Q4.
