Really basic trig question

OK:

arsin(sin(5p\7)) = 2p/7

arctan(tan(5p/5))= -p/5

Why is the second answer negative?

Re: Really basic trig question

Quote:

Originally Posted by

**Nervous** OK:

arsin(sin(5p\7)) = 2p/7

arctan(tan(5p/5))= -p/5

Why is the second answer negative?

The angle must be in the second quadrant...

Re: Really basic trig question

Quote:

Originally Posted by

**Nervous** OK:

arsin(sin(5p\7)) = 2p/7

**arctan(tan(5p/5))= -p/5**

Why is the second answer negative?

uhhh ... arctan((tan(5pi/5)) = \arctan(tan(pi)) = \arctan(0) = 0

Re: Really basic trig question

Quote:

Originally Posted by

**skeeter** uhhh ... arctan((tan(5pi/5)) = \arctan(tan(pi)) = \arctan(0) = 0

I must have misunderstood the question, I thought that p was representing some unknown, not $\displaystyle \displaystyle \begin{align*} \pi \end{align*} $...

Re: Really basic trig question

Quote:

Originally Posted by

**Prove It** I must have misunderstood the question, I thought that p was representing some unknown, not $\displaystyle \displaystyle \begin{align*} \pi \end{align*} $...

first solution is ... Quote:

arsin(sin(5p\7)) = 2p/7

what else could "p" be?