Mathematics
8 Online
OpenStudy (anonymous):
List the discontinuities for the function f(x) = cot(5x/3 ).
11 years ago
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OpenStudy (anonymous):
\[\cot\frac{ 5x }{ 3 }\]
11 years ago
OpenStudy (cwrw238):
what is the value when x = 0?
11 years ago
OpenStudy (anonymous):
THESE are the answeres:
a. There are no discontinuities.
b. n(pi/2), where n is an integer
c. n(pi/3), where n is an integer
d. n(three(pi)/5), where n is an integer
11 years ago
OpenStudy (anonymous):
how?
11 years ago
OpenStudy (anonymous):
@l_o_w_key @cwrw238
11 years ago
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myininaya (myininaya):
cot(x)=cos(x)/sin(x)...
you need to basically solve
\[\sin(\frac{5x}{3})=0\]
11 years ago
OpenStudy (anonymous):
what happened to cos?
11 years ago
OpenStudy (anonymous):
@myininaya
11 years ago
myininaya (myininaya):
you can't divide by 0
11 years ago
myininaya (myininaya):
you have sin(5x/3) on bottom
11 years ago
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myininaya (myininaya):
you cannot have sin(5x/3)=0
11 years ago
OpenStudy (anonymous):
i still dont get it
11 years ago
OpenStudy (anonymous):
@myininaya
11 years ago
myininaya (myininaya):
\[\cot(\frac{5x}{3})=\frac{\cos(\frac{5x}{3})}{\sin(\frac{5x}{3})}\]
agreed?
11 years ago
OpenStudy (anonymous):
ya
11 years ago
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OpenStudy (solomonzelman):
no
11 years ago
myininaya (myininaya):
a fraction is discontinuous when its bottom is 0
11 years ago
myininaya (myininaya):
\[\sin(\frac{5x}{3})=0 \text{ will give discontinuites }\]
11 years ago
OpenStudy (solomonzelman):
oh, sorry
11 years ago
OpenStudy (solomonzelman):
it's cotangent, I thought it was cosine
11 years ago
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OpenStudy (solomonzelman):
I should pay more attention to the questions.
11 years ago
OpenStudy (anonymous):
okay so how do i solve the problem to get the answer?
11 years ago
myininaya (myininaya):
let u=5x/3
do you know how to solve sin(u)=0
11 years ago
myininaya (myininaya):
when you are done solve sin(u)=0 for u
then you can finish up by replacing u with 5x/3
then solve for x
11 years ago
OpenStudy (anonymous):
i dont know how to do tht
11 years ago
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OpenStudy (anonymous):
how do u do tht
11 years ago
myininaya (myininaya):
go to your unit circle and find for what angles is sine (the y-coordinate ) 0
11 years ago
OpenStudy (anonymous):
squareroot 3/2
11 years ago
myininaya (myininaya):
that's an angle?
11 years ago
myininaya (myininaya):
I think you just randomly chose a value within one of the ordered pairs
11 years ago
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myininaya (myininaya):
I'm asking you to find angle(s) on the unit circle for which the y-coordinate is 0 (0 means zero)
11 years ago
OpenStudy (anonymous):
120 and 300
11 years ago
myininaya (myininaya):
sin(120) is not zero
sin(300) is also not zero
11 years ago
OpenStudy (anonymous):
ohh okay so its 180 and 360
.
11 years ago
OpenStudy (anonymous):
???
11 years ago
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myininaya (myininaya):
yes and you can also so 0 right?
11 years ago
myininaya (myininaya):
0,180,360,...
or 180*n
where n is an integer
11 years ago
myininaya (myininaya):
I think they want it in radians so convert that to radians
11 years ago
myininaya (myininaya):
\[\frac{5x}{3}=\pi n\]
11 years ago
myininaya (myininaya):
finish solving for x and you are done
11 years ago
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OpenStudy (anonymous):
so its pi/2?
11 years ago
myininaya (myininaya):
trying to think how you got that after solving for x
11 years ago
myininaya (myininaya):
to undo the division by 3 multiply by 3 on both sides
to undo the multiplication by 5 you divide both sides by 5
11 years ago
myininaya (myininaya):
|dw:1419281569635:dw|
11 years ago