Limits of sin(x)sin(1/x) when x approaches 0

Clash Royale CLAN TAG#URR8PPP
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I came across this problem as shown in the title.
Limit of sin(x)sin(1/x) as x approaches 0. I plot the graph using online graphing calculators and found that it is approaching zero. But can anybody please proof it? I am really stuck and don't know where to start.
Also I did try to search the internet and found that the limit of xsin(1/x) equals to zero as x approaches zero. I understand how that work. So my second question is can I say that limit of
sin(x)sin(1/x) is the same as limit xsin(1/x) when x approaches zero, since limit of sin(x)/x equals 1 when x approaches zero?
limits
add a comment |Â
up vote
0
down vote
favorite
I came across this problem as shown in the title.
Limit of sin(x)sin(1/x) as x approaches 0. I plot the graph using online graphing calculators and found that it is approaching zero. But can anybody please proof it? I am really stuck and don't know where to start.
Also I did try to search the internet and found that the limit of xsin(1/x) equals to zero as x approaches zero. I understand how that work. So my second question is can I say that limit of
sin(x)sin(1/x) is the same as limit xsin(1/x) when x approaches zero, since limit of sin(x)/x equals 1 when x approaches zero?
limits
5
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
thanks a lot everyone
â JoisBack
Sep 4 at 7:25
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I came across this problem as shown in the title.
Limit of sin(x)sin(1/x) as x approaches 0. I plot the graph using online graphing calculators and found that it is approaching zero. But can anybody please proof it? I am really stuck and don't know where to start.
Also I did try to search the internet and found that the limit of xsin(1/x) equals to zero as x approaches zero. I understand how that work. So my second question is can I say that limit of
sin(x)sin(1/x) is the same as limit xsin(1/x) when x approaches zero, since limit of sin(x)/x equals 1 when x approaches zero?
limits
I came across this problem as shown in the title.
Limit of sin(x)sin(1/x) as x approaches 0. I plot the graph using online graphing calculators and found that it is approaching zero. But can anybody please proof it? I am really stuck and don't know where to start.
Also I did try to search the internet and found that the limit of xsin(1/x) equals to zero as x approaches zero. I understand how that work. So my second question is can I say that limit of
sin(x)sin(1/x) is the same as limit xsin(1/x) when x approaches zero, since limit of sin(x)/x equals 1 when x approaches zero?
limits
limits
asked Sep 4 at 7:14
JoisBack
1355
1355
5
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
thanks a lot everyone
â JoisBack
Sep 4 at 7:25
add a comment |Â
5
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
thanks a lot everyone
â JoisBack
Sep 4 at 7:25
5
5
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
thanks a lot everyone
â JoisBack
Sep 4 at 7:25
thanks a lot everyone
â JoisBack
Sep 4 at 7:25
add a comment |Â
2 Answers
2
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up vote
3
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HINT
Let observe that since $forall theta: , |sin theta|le 1$
$$0le |sin x cdot sin(1/x)|=|sin x| cdot |sin(1/x)|le |sin x|$$
then refer to squeeze theorem.
Note that the result you are referring to, that is
$$xcdot sinleft(frac1xright)to 0$$
can be obtained in the same way by squeeze theorem
$$0le |x cdot sin(1/x)|=|x| cdot |sin(1/x)|le |x|to 0$$
once we know that, we can also proceed by standards limit and conclude that
$$sin x cdot sinleft(frac1xright)=fracsin xx cdot x cdot sinleft(frac1xright)to 1 cdot 0 = 0$$
but it is a pretty convolute way since we can apply directly the squeeze theorem to the given limit.
add a comment |Â
up vote
2
down vote
HINT:
$$
|sin xsin(1/x)|leq|x|cdot|sin(1/x)|
$$
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
HINT
Let observe that since $forall theta: , |sin theta|le 1$
$$0le |sin x cdot sin(1/x)|=|sin x| cdot |sin(1/x)|le |sin x|$$
then refer to squeeze theorem.
Note that the result you are referring to, that is
$$xcdot sinleft(frac1xright)to 0$$
can be obtained in the same way by squeeze theorem
$$0le |x cdot sin(1/x)|=|x| cdot |sin(1/x)|le |x|to 0$$
once we know that, we can also proceed by standards limit and conclude that
$$sin x cdot sinleft(frac1xright)=fracsin xx cdot x cdot sinleft(frac1xright)to 1 cdot 0 = 0$$
but it is a pretty convolute way since we can apply directly the squeeze theorem to the given limit.
add a comment |Â
up vote
3
down vote
HINT
Let observe that since $forall theta: , |sin theta|le 1$
$$0le |sin x cdot sin(1/x)|=|sin x| cdot |sin(1/x)|le |sin x|$$
then refer to squeeze theorem.
Note that the result you are referring to, that is
$$xcdot sinleft(frac1xright)to 0$$
can be obtained in the same way by squeeze theorem
$$0le |x cdot sin(1/x)|=|x| cdot |sin(1/x)|le |x|to 0$$
once we know that, we can also proceed by standards limit and conclude that
$$sin x cdot sinleft(frac1xright)=fracsin xx cdot x cdot sinleft(frac1xright)to 1 cdot 0 = 0$$
but it is a pretty convolute way since we can apply directly the squeeze theorem to the given limit.
add a comment |Â
up vote
3
down vote
up vote
3
down vote
HINT
Let observe that since $forall theta: , |sin theta|le 1$
$$0le |sin x cdot sin(1/x)|=|sin x| cdot |sin(1/x)|le |sin x|$$
then refer to squeeze theorem.
Note that the result you are referring to, that is
$$xcdot sinleft(frac1xright)to 0$$
can be obtained in the same way by squeeze theorem
$$0le |x cdot sin(1/x)|=|x| cdot |sin(1/x)|le |x|to 0$$
once we know that, we can also proceed by standards limit and conclude that
$$sin x cdot sinleft(frac1xright)=fracsin xx cdot x cdot sinleft(frac1xright)to 1 cdot 0 = 0$$
but it is a pretty convolute way since we can apply directly the squeeze theorem to the given limit.
HINT
Let observe that since $forall theta: , |sin theta|le 1$
$$0le |sin x cdot sin(1/x)|=|sin x| cdot |sin(1/x)|le |sin x|$$
then refer to squeeze theorem.
Note that the result you are referring to, that is
$$xcdot sinleft(frac1xright)to 0$$
can be obtained in the same way by squeeze theorem
$$0le |x cdot sin(1/x)|=|x| cdot |sin(1/x)|le |x|to 0$$
once we know that, we can also proceed by standards limit and conclude that
$$sin x cdot sinleft(frac1xright)=fracsin xx cdot x cdot sinleft(frac1xright)to 1 cdot 0 = 0$$
but it is a pretty convolute way since we can apply directly the squeeze theorem to the given limit.
edited Sep 4 at 8:39
answered Sep 4 at 7:17
gimusi
72.8k73889
72.8k73889
add a comment |Â
add a comment |Â
up vote
2
down vote
HINT:
$$
|sin xsin(1/x)|leq|x|cdot|sin(1/x)|
$$
add a comment |Â
up vote
2
down vote
HINT:
$$
|sin xsin(1/x)|leq|x|cdot|sin(1/x)|
$$
add a comment |Â
up vote
2
down vote
up vote
2
down vote
HINT:
$$
|sin xsin(1/x)|leq|x|cdot|sin(1/x)|
$$
HINT:
$$
|sin xsin(1/x)|leq|x|cdot|sin(1/x)|
$$
answered Sep 4 at 7:17
Przemysà Âaw Scherwentke
11.8k52751
11.8k52751
add a comment |Â
add a comment |Â
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5
Observe that $|sin(1/x)| leq 1$, so $|sin(x)sin(1/x)| leq |sin(x)|$.
â Bungo
Sep 4 at 7:16
thanks a lot everyone
â JoisBack
Sep 4 at 7:25