skipdnelson: how do u find cos(x) if cot(x)=-3/4
I think that the easiest way is to ignore the minus sign just for a moment.
Now,
Draw a right angled triangle, let one of the acute angels be x.
put 3 and 4 on the correct sides for Cot.
find the other side, use pythagoras if you need to but it is easy.
Read cos x straight off your triangle.
Now you can't ignore the minus any longer.
Cot x is negative
If cot x is negative then 1/cotx which is tan x must also be negative.
In which quadrants is tanx negative?
Will cos x be positive or negative in those quadrants?
Hopefully that will be enough for you to answer your question.
+118654 
