# Trigonometry math help.. confirmation?

• Mar 4th 2011, 05:35 PM
ASUSpro
Trigonometry math help.. confirmation?
i been trying to solve this but can't seem to get the wrong answer, can anyone help me located where i went wrong?

3cot^2(x)=1 , x is greater than or equal to 0 and less than 2pi

cot(x) = 1/square root 3

x = 60 degree or pi / 3

shouldn't the 4 answers be pi/3, -2pi/3, 4pi/3, and -5pi/3
correct me if im wrong please. thank you!
• Mar 4th 2011, 05:43 PM
topsquark
Quote:

Originally Posted by ASUSpro
i been trying to solve this but can't seem to get the wrong answer, can anyone help me located where i went wrong?

3cot^2(x)=1 , x is greater than or equal to 0 and less than 2pi

cot(x) = 1/square root 3

x = 60 degree or pi / 3

shouldn't the 4 answers be pi/3, -2pi/3, 4pi/3, and -5pi/3
correct me if im wrong please. thank you!

Two of these are correct. Note that your solution set needs to be $0 \leq \theta < 2 \pi$. What does this do to your negative solutions?

-Dan
• Mar 4th 2011, 05:46 PM
ASUSpro
I can't add 360 degree , that wil make them out of range, do i just remove the negative signs?
• Mar 4th 2011, 06:00 PM
topsquark
Quote:

Originally Posted by ASUSpro
I can't add 360 degree , that wil make them out of range, do i just remove the negative signs?

The solution $-2 \pi /3$ is in QIII, so we have a reference angle of $\pi /3$ below the -x axis. Thus the angle $-2 \pi /3$ is the same as $\pi + \pi / 3 = 4 \pi / 3$ which is already on your list.

-Dan