Question 1040287
<pre>
The x-coordinate, 3, is the adjacent side.
The y-coordinate, -4, is the opposite side.
The hypotenuse is worked out with the Pythagorean theorem:

{{{hypotenuse}}}{{{""=""}}}{{{sqrt(adjacent^2+opposite^2)}}} 
{{{hypotenuse}}}{{{""=""}}}{{{sqrt((3)^2+(-4)^2)}}}
{{{hypotenuse}}}{{{""=""}}}{{{sqrt(9+16)}}}
{{{hypotenuse}}}{{{""=""}}}{{{sqrt(25)}}}
{{{hypotenuse}}}{{{""=""}}}{{{5}}}

And we want the cosine.

We learned that {{{cosine}}}{{{""=""}}}{{{adjacent/hypotenuse}}}

So the cosine is 

{{{cosine}}}{{{""=""}}}{{{adjacent/hypotenuse}}}{{{""=""}}}{{{3/5}}}

Edwin</pre>