Plot the point (-7, -5). We are in quadrant 3.
We also know that tan θ = opp/adj.
Cot θ = adj/opp.
Let us use a^2 + b^2 = r^2 to show you how to find r, the radius aka hypotenuse.
Look: (-7)^2 + (-5)^2 = r^2
If you should ever need to find r, do this:
(-7)^2 + (-5)^2 = r^2
(49) + 25) = r^2
74 = r^2
Take the square root on both sides of the equation to find r.
sqrt{74} = sqrt{r^2}
sqrt{74} = r
It is ok to simplify the sqrt{74} but not needed.
We now have the three sides of the triangle that is form in quadrant 3.
We can now read cot θ from the triangle itself.
So, cot θ = adj/opp = (-7)/(-5) or 7/5.
No need to find r but I simply wanted to show you how it's done in case you are given a question where r must be found.