We draw an angle in the 4th quadrant like below. Since the cotangent is the
adjacent over the opposite, or
, we make the given cotangent,-3, into a
fraction
, but in quadrant IV, x goes right and y goes down, so the
numerator x is positive and the denominator y is negative, so we change the
to
and make the numerator
+3 be the value of x and the denominator -1 be the value of y.
so we have:

Now we need to know that
the sine is the opposite over the hypotenuse or y/r, which is
or
.
the cosine is the adjacent over the hypotenuse or x/r, which is
or
.
the tangent is the opposite over the adjacent or y/x, which is
or
.
the secant is the hypotenuse over the adjacent or r/x, which is
.
the cosecant is the hypotenuse over the opposite or r/y, which is
or
.
Edwin