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OpenStudy (studygurl14):
OpenStudy (studygurl14):
@TheSmartOne @jim_thompson5910 @SolomonZelman
OpenStudy (studygurl14):
@TheSmartOne @Mertsj @jim_thompson5910
OpenStudy (mertsj):
Factor out tan(x)
OpenStudy (studygurl14):
Oh, thanks! I'll try that
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OpenStudy (mertsj):
yw
OpenStudy (studygurl14):
@Mertsj I'm stuck.
I got this:
tan x (sec x -2) = 0
tan x = 0
x = 0
sec x - 2 = 0
sec x = 2
?
TheSmartOne (thesmartone):
I don't know anything about this :/ Sorry..
OpenStudy (freckles):
\[\tan(x)=0 \\ \cos(x)=\frac{1}{2}\]
OpenStudy (freckles):
are the equations you have to solve
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OpenStudy (misty1212):
if \(\sec(x)=2\) then \(\cos(x)=\frac{1}{2}\)
OpenStudy (freckles):
and actually we can just say solve sin(x)=0 and solve cos(x)=1/2
OpenStudy (misty1212):
all your choices have \[0+k\pi\] from the \(\tan(x)=0\)
OpenStudy (studygurl14):
oh, right. thanks. don't know where my brain is
OpenStudy (jhannybean):
Correction: \[\tan(x) = 0 \implies x =\tan^{-1}(0)\]
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OpenStudy (studygurl14):
x = 60 then...which is pi/3 in radians
OpenStudy (freckles):
also your choices are weird
OpenStudy (jhannybean):
You had written \[\tan(x) = 0\]\[x=0\]
OpenStudy (studygurl14):
Would the answer be B or D?
OpenStudy (freckles):
none of your choices make any sense
one of your choices are close
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OpenStudy (freckles):
but it is still not correct
OpenStudy (jhannybean):
Ok first off, what is the first value when \(x =\tan^{-1}(0)\)?
OpenStudy (studygurl14):
0 ^
OpenStudy (jhannybean):
And what are your domain restrictions? \([0,2\pi)\)?
OpenStudy (studygurl14):
I don't think there are any? ^
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OpenStudy (mertsj):
If tan x = 0 then x is 0 or pi
If sec x = 2 then cos x = 1/2 and x = pi/3 or 5pi/3
OpenStudy (studygurl14):
This all makes some sense to me, bu none of it is in the answer choices...ugh
OpenStudy (freckles):
hint:
cos(x) is even
so you could say cos(x)=cos(-x)
but none of your choices will work
OpenStudy (freckles):
because k can't be irrational and an integer at the same time
OpenStudy (jhannybean):
Yes, there is a correct answer choice in that bunch
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OpenStudy (studygurl14):
since x = pi/3, would x also work for any value that was (pi k)/3 ???
OpenStudy (studygurl14):
k equaling 1, 2, 3 , etc?
OpenStudy (jhannybean):
you're on the right track.
OpenStudy (studygurl14):
That's why I was thinking B or D ^
OpenStudy (freckles):
there is not a correct choice ...
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OpenStudy (anonymous):
You know, only one of the given solutions actually make sense.
OpenStudy (studygurl14):
D? ^
OpenStudy (jhannybean):
Well, if you think it is D, then plug in values for k that satisfy both x = 0 and x = 1/2
OpenStudy (anonymous):
For example first option has \(2k+\pi/3\).
OpenStudy (freckles):
2kpi+pi/3
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OpenStudy (freckles):
should be that ^
OpenStudy (anonymous):
No way \(2k\) makes any sense.
OpenStudy (studygurl14):
@Jhannybean I plugged in 1 for k + pi/3, and it worked. I got 0
OpenStudy (jhannybean):
:)
OpenStudy (freckles):
a lot of the thingys are missing pi
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OpenStudy (studygurl14):
Thanks @Jhannybean
OpenStudy (jhannybean):
Keep going @StudyGurl14
OpenStudy (jhannybean):
Wait a minute, do you understand, @freckles ?
OpenStudy (jhannybean):
If not, explain @StudyGurl14 :)
OpenStudy (freckles):
Yes I been saying done of these choices are correct... lol.
but one of them is kinda close.
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OpenStudy (freckles):
none*
OpenStudy (studygurl14):
Wait @Jhannybean It can't be D...cause I plugged in 2 for k, and it didn't work. it didn't result in 0
OpenStudy (studygurl14):
wait, hold on i made a mistake
OpenStudy (jhannybean):
But you have two conditions to satisfy, do you not?
OpenStudy (studygurl14):
It's not D, I don't think...
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OpenStudy (studygurl14):
I'm back to thinking it is B, but even that doesn't work right...*sigh*
OpenStudy (freckles):
this is what I'm saying...
the choices should look like this:
\[A) 0+\pi k , 2k \pi+\frac{\pi}{3}, 2k \pi-\frac{\pi}{3} \\ B)0+\pi k, \frac{\pi k}{3}, \frac{2 \pi k}{3} \\ C) 0+ \pi k, 2k \pi+\frac{\pi}{3}, k \pi+\frac{2\pi}{3} \\ D) 0+\pi k , k \pi +\frac{\pi}{3}, k \pi +\frac{2\pi}{3}\]
OpenStudy (studygurl14):
I don't think so @freckles ...
OpenStudy (studygurl14):
Why would they need two pi's?
OpenStudy (mertsj):
If tan x = 0 then x is 0 or pi
\[0^{o}+\pi k\]
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OpenStudy (mertsj):
If sec x = 2 then cos x = 1/2 and x = pi/3 or 5pi/3
OpenStudy (freckles):
pi/3+2pi*k
this explains all the angles that end up at that one particular coordinate (1/2, sqrt(3)/2)
this tells us that
the following are solutions
pi/3
pi/3+2pi
pi/3+4pi
and so on...
if we go pi/3 and then 2pi/3 we land at the same location we stopped at before
OpenStudy (mertsj):
x=pi/3
\[\frac{\pi}{3} +2k \pi \]
OpenStudy (freckles):
pi/3+2 makes no sense at all
OpenStudy (studygurl14):
Okay, so I used mathway, and it says this:
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OpenStudy (mertsj):
5pi/3 is the same as - pi/3
OpenStudy (studygurl14):
BUT, that's not an answer choice....*sigh*
OpenStudy (freckles):
oops /3 was a type-o
OpenStudy (mertsj):
So choose the first answer and be done with it already
OpenStudy (freckles):
cos(x)=cos(-x)
so if pi/3 is a solution then -pi/3 is also a solution
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OpenStudy (freckles):
but i would still say none of these and put the write solution :p
OpenStudy (freckles):
right
OpenStudy (jhannybean):
That's what @Mertsj is saying,
OpenStudy (studygurl14):
OH! So then A
OpenStudy (freckles):
but it really isn't A
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OpenStudy (freckles):
but A is the closest
OpenStudy (studygurl14):
I see. Thanks.
OpenStudy (freckles):
\[2\pi n+\frac{\pi}{3} , 2 \pi n+\frac{-\pi}{3}\]
OpenStudy (studygurl14):
It was A...man if that was the practice test, I'm afraid of the real thing...haha
OpenStudy (freckles):
hopefully there won't be any type-os :p
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OpenStudy (studygurl14):
yeah...stupid Connections Academy...
OpenStudy (anonymous):
If it was a real test, then you'd have to tell a teacher that the answers are wrong.