# Refrence Angles & Positive/Negative Angles(Coterminals) HOW?

1. Jun 2, 2004

### mathzeroh

my question is, how do you "Find one positive angle and one negative angle that are coterminal with each angle." :

For example:

$$\frac{5\pi}{12}$$

And also, I had a question on this as well:

Find the reference angle for each angle with the given measure.
$$\frac{12\pi}{5}$$

i noe that you have to see what quadrant it is in, then from there, you use the Reference Angle Rule, whichever one. But what if the measure is a negative number? Like for example, $$-210\circ$$?? What would you do here?

if anyone can help me with these i'd be really gratefull! thanks!!

2. Jun 3, 2004

### AKG

Given some angle, x, you can find a positive angle co-terminal with x by adding $2\pi$ to x until you get a positive number, and you can figure out how to find a negative angle.
To find the reference angle for any angle, keep continuing to add or subtract $2\pi$ until you get a value, x, such that $0 \leq x < 2\pi$. Of course, you'll have to figure out whether you need to add, subtract, or neither.