Coterminal angles, question posted below

Question

sleepyjess · Answer

Find the measures of two angles, one positive and one negative, that are coterminal with
$\pi/6$

$13\pi/6; -\pi/6\$
$\dfrac{\pi}{6} +360; \dfrac{\pi}{6} -360\$
$\dfrac{7\pi}{6}\dfrac{-5\pi}{6}\$
$\dfrac{13\pi}{6}\dfrac{-11\pi}{6}$

sleepyjess · Answer

I think it is either B or C

sleepyjess · Answer

And there are 2 fractions in each option

sleepyjess · Answer

@satellite73

e.mccormick · Answer

OK,  So, it is in radians.  For radians you add or subtract $2\pi$.

e.mccormick · Answer

However, that is a fraction.  So rulesabout fractions apply.  Did you get the common denominator then add and subtract?  And no, I did not do this so I am asking what you did.

e.mccormick · Answer

I don't like b because it has radians and number.  Usually you stilc to degrees or radians and not do a mashup.

sleepyjess · Answer

I was thinking that it should be $-\dfrac{\pi}{6}$ and $\dfrac{3\pi}{6}$ but that isn't an option

thesmartone · Answer

I don'tknow anything about trig :/

e.mccormick · Answer

Well... to get it over 6, remember things like this?

$\dfrac{6}{6}\cdot\dfrac{2\pi}{1}$ ?

e.mccormick · Answer

AKA: getting a common denominator.

sleepyjess · Answer

Isn't the denominator already the same though?

e.mccormick · Answer

Ummm... you have:

$\dfrac{\pi}{6}\pm 2\pi$ which means $\dfrac{\pi}{6}\pm \dfrac{2\pi}{1}$, so no.

sleepyjess · Answer

Oh, so $\dfrac{\pi}{6}+\dfrac{12\pi}{6}$ and $\dfrac{\pi}{6}-\dfrac{12\pi}{6}$?

e.mccormick · Answer

$\overset{\text{^ ^}}\smile$

sleepyjess · Answer

Which would be $\dfrac{13\pi}{6}$ and $\dfrac{-11\pi}{6}$

e.mccormick · Answer

$\huge\overset{_\text{^ ^}}{\overset{\cdot}\smile}$

sleepyjess · Answer

Yay!

e.mccormick · Answer

Two things to remember:  1 likes to hide.  1 had many forms.

So that 1 on the bottom of the fraction I did.  It was alwas there, but hidden.  And that 6/6 is really just 1.

sleepyjess · Answer

Ok. Thank you!

e.mccormick · Answer

And sometimes they make these more tricky by making it some other multiple.... like if you have to add 4pi rather than 2pi... =(

sleepyjess · Answer

huh?

e.mccormick · Answer

I am saying, they could have made an answer say $\dfrac{25\pi}{6}$ to make the question more tricky.  If you do not see it one step to either side, look out for that.

sleepyjess · Answer

wow

e.mccormick · Answer

That is just one more cotermanal higher.  =)  So not way out there... but I have seen teachers use it for a "tricky" question.