## gjhfdfg 2 years ago Finding the exact value of trig. functions?

1. gjhfdfg

I have this I'm trying to figure out, $\cot (- \frac{ 5 \pi }{ 4 } )$

2. Marx

it's $\cot(-\frac{5}{4}\pi) = \frac{\cos(-\frac{5}{4}\pi)}{\sin(-\frac{5}{4}\pi)}$ can you find those?

3. gjhfdfg

Wouldnt it just cancel out?

4. Marx

if by cancel out you mean will give -1 , then yeah :) remember : cos(-x) =cosx

5. gjhfdfg

Nope thats not what I meant lol But thanks

6. Marx

yeah I figured that, my point was that $\cos(-\frac{5}{4}\pi)=\cos(\frac{5}{4}\pi)=\frac{1}{\sqrt{2}}$ and $\sin(-\frac{5}{4}\pi)=-\frac{1}{\sqrt{2}}$

7. gjhfdfg

I was thinking that the - 5/4 pi cancels out for some reason