Double integration problem

BvU
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2019 Award
Pity you don't post your drawing ...

do u ask me to draw out ##x\over \sqrt{x^2 + y^2} ## ???
If so , i really dun know how to draw it out ....

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Pity you don't post your drawing ...
this one ?

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BvU
Homework Helper
2019 Award
No, this one:

draw a point ##\ x,y \ ## and consider what ##\
x\over \sqrt{x^2 + y^2} ## represents
Since words fail me, I will try it with a picture:

 your picture looks cute, but why do you set the ranges to -50,50 instead of x -2,2 and y 0,2 ?

Last edited:
No, this one:

Since words fail me, I will try it with a picture:

View attachment 105789

 your picture looks cute, but wht do you set the ranges to -50,50 instead of x -2,2 and y 0,2 ?
So, how to proceed from ur diagram?

BvU
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2019 Award
what ##\ x\over \sqrt{x^2 + y^2} ##represents

it has no meaning , right ? the author just simply put inside the equation, right ?

BvU
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2019 Award
You think I annoy you with so many questions when there is no meaning ? What is the sine of the red angle ? What is the cosine ?

You think I annoy you with so many questions when there is no meaning ? What is the sine of the red angle ? What is the cosine ?
View attachment 105794
It's cos theta, so?

Ray Vickson
Homework Helper
Dearly Missed
It's cos theta, so?
What do you think?

Mark44
Mentor
@chetzread, I believe that BvU's hint is not about merely switching the order of integration (i.e., dxdy vs. dydx), but instead, about changing to a polar integral. This problem quite a bit easier if you do it this way.

BvU
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2019 Award
It's cos theta, so?
So ? Wouldn't substituting ##\theta## as integration variable be a sensible thing to try ?

So ? Wouldn't substituting ##\theta## as integration variable be a sensible thing to try ?
ok, i got the ans now ....I'm wondering is this a special case? I have never learnt and see this before ...

BvU
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2019 Award
Humor me and tell me what you did ...

Humor me and tell me what you did ...

BvU