Mathematics
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OpenStudy (anonymous):
Solve the following equation on the interval [0,2pi).
sin x-2 sin x cos x = 0
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OpenStudy (xapproachesinfinity):
how about factoring that sinx
what do get if you did
OpenStudy (anonymous):
1-cos x?
OpenStudy (xapproachesinfinity):
where did sinx go
\[\sin x(1-2\cos x)=0\]
OpenStudy (xapproachesinfinity):
set EACH ONE EQUAL TO ZERO
OpenStudy (xapproachesinfinity):
and solve
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OpenStudy (xapproachesinfinity):
let me see your work!
OpenStudy (anonymous):
how did you get sin x (1-2cos x)=0?
OpenStudy (xapproachesinfinity):
i factored sinx my friend
OpenStudy (anonymous):
wait did you subtract 2sin x from sin x?
OpenStudy (xapproachesinfinity):
no do you know how to factor?
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OpenStudy (anonymous):
Yeah I can factor, but I get confused with trigonometric functions
OpenStudy (xapproachesinfinity):
how do you factor \[x-2xy\]
OpenStudy (xapproachesinfinity):
say how would you factor?
OpenStudy (anonymous):
I have no idea
OpenStudy (xapproachesinfinity):
you just said you know how to do it, but you only have issue with trig
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OpenStudy (xapproachesinfinity):
that's not trig just a linear expression
OpenStudy (anonymous):
I can factor equations like x^2+3x+3
OpenStudy (xapproachesinfinity):
well if you can factor that why can't you factor x-2xy? what is common btw x and -2xy?
OpenStudy (anonymous):
the x's
OpenStudy (xapproachesinfinity):
yes so can we then factor the x's
and get x(1-2y)
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OpenStudy (xapproachesinfinity):
if i factored x in the first i'm left with 1
if i factored x in the second term i'm left with -2y
OpenStudy (anonymous):
sorry my net cut out
OpenStudy (anonymous):
sin x=0 cosx= 1/2
OpenStudy (anonymous):
0, pi, pi/6, 5pi/6 is what I got
OpenStudy (xapproachesinfinity):
show your work?
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OpenStudy (anonymous):
I just used the unit circle?
OpenStudy (xapproachesinfinity):
show the whole work my friend, you skipped many steps
OpenStudy (anonymous):
sin x=0
1-2cosx=0
-2cosx=-1
cox x=1/2
?
OpenStudy (xapproachesinfinity):
yes and then?
OpenStudy (anonymous):
I just used the unit circle, sinx=0 is at pi and 0 and cosx=1/2 is at pi/3 and 5pi/3
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OpenStudy (anonymous):
damn I messed it up lol
OpenStudy (xapproachesinfinity):
what about 2pi?
OpenStudy (xapproachesinfinity):
for sin
OpenStudy (xapproachesinfinity):
isn't zero as well
OpenStudy (xapproachesinfinity):
and it is pi/6 not pi/3 the first answer you provided was correct except that you missed 2pi
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OpenStudy (anonymous):
Yeah I got 0, 2pi I'm assuming because it's [0,2pi)?
OpenStudy (xapproachesinfinity):
oh it is open i didn't see that
then you are good
OpenStudy (anonymous):
alright thanks, can you help me with one more?
OpenStudy (anonymous):
sin(2x+pi/6)=1/2 no idea how to even begin
OpenStudy (xapproachesinfinity):
when does an angles give 1/2 when you sin it?
and is there and interval given (because you have to make sure the values are in that interval)
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OpenStudy (anonymous):
interval is [0,2pi) and pi/6 and 5pi/6
OpenStudy (xapproachesinfinity):
then 2x+pi/6=pi/6 or 2x+pi/6=5pi/6
OpenStudy (xapproachesinfinity):
solve for x
OpenStudy (anonymous):
x=2 or x=4pi/3 ?
OpenStudy (xapproachesinfinity):
how come x=2?
2x=0 how did you get x=2?
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OpenStudy (anonymous):
I read it wrong, oops
OpenStudy (anonymous):
so sin of 0 and sin of 4pi/3?
OpenStudy (xapproachesinfinity):
hmm no
x=0 and x=4pi/6=2pi/3
OpenStudy (anonymous):
I thought 4pi was its own entity? I'm doing online math so I'm essentially teaching everything to myself so sorry for the lack of math experience
OpenStudy (xapproachesinfinity):
oh no problem
you did good you just didn't simplify nicely
5pi/6-pi/6 =4pi/6 not 4pi/3
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OpenStudy (anonymous):
so the next step would be to get the sin of both angles?
OpenStudy (anonymous):
or the sin of 1/2?
OpenStudy (xapproachesinfinity):
you are done what else you want?
they asked you to find x and you found it??
OpenStudy (anonymous):
why is the answer 0,pi/3,pi,4pi/3? I thought it was 2pi/3?
OpenStudy (anonymous):
where did the pi/3 and 4pi/3 come from?