# Thread: Quick question: Coterminal angles

1. ## Quick question: Coterminal angles

How do you find coterminal angles (in radians and degrees)?

2. Originally Posted by aikenfan
How do you find coterminal angles (in radians and degrees)?
to find coterminal angles in radians, you add or subtract $\displaystyle 2 \pi$ as many times as is needed.

to find coterminal angles in degrees, add or subtract 360 degrees as many times as is needed

3. What about complementary angles and supplementary angles (in place of coterminal in this question)...would it be the same?

4. Originally Posted by aikenfan
What about complementary angles and supplementary angles (in place of coterminal in this question)...would it be the same?
these are totally different things

complementary angles are angles that add up to 90 degrees (or $\displaystyle \frac {\pi}2$ radians)

supplementary angles are angles that add up to 180 degrees (or $\displaystyle \pi$ radians)

5. so how do you find How do you find supplementary angles (in radians and degrees)?

6. Originally Posted by aikenfan
so how do you find How do you find supplementary angles (in radians and degrees)?
it really depends on the question. usually you would be given an angle in some way, and then they would tell you that it is supplementary to some other angle and then you would use the definition i said.

example. Given that A and B are supplementary angles. If A = 30 degrees, what is B?

here you would have A + B = 180 => 30 + B = 180 => B = 150 degrees

example. Given that A and B are supplementary angles measured in degrees, if A = 2x + 1 and B = x + 5, find x.

again you would set A + B = 180 => 2x + 1 + x + 5 = 180 and solve for x

the questions you get might not be that simple, but that's the gist of it. if angles are supplementary, you can equate their sum to 180 degrees or pi radians. similarly for complimentary angles, you can equate their sum to 90 degrees or pi/2 radians

7. Thats the thing, there wasn't a question...it just asked to explain how to find them...I couldn't find it anywhere, I tried google etc...

8. Originally Posted by aikenfan
Thats the thing, there wasn't a question...it just asked to explain how to find them...I couldn't find it anywhere, I tried google etc...
well...i guess you should just explain that you determine them in respect to other angle(s). so basically just say that you have to make sure the total sum of all the supplementary angles add up to 180 degrees ... complimentary add up to 90 degrees...blah blah blah

9. Thank you so much for all of your help...I could not find the answer to this anywhere...I appreciate you taking the time to help!