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# Circles (equations of) watch

1. I'm trying to find out the equation of a specific bit of a circle...

I have the circle (1) which is a circle with radius 1 centred around (1,0).

I need an expression, , for the the top right quarter of the circle. For the life in me I can't find it.

The original equation i was given was (2), which I decided was equivalent to (1) if .

I've tried simply rearranging and thought about inverses and such but I think I'm going round in circles.

Any hints?
2. http://www.thestudentroom.co.uk/show...6&postcount=34

^ there I've found limits for a similar circle

edit: I realise I didn't read, you want to integrate wrt x first for some reason
3. Ummm... you could just specify the values of x and y so that you can only get that part of the circle?
4. (Original post by nota bene)
http://www.thestudentroom.co.uk/show...6&postcount=34

^ there I've found limits for a similar circle
I like how you knew I was finding limits
I'm not sure I can usr your example, though.
For my problem the logical way would be to fix values of x and find limits of y - it's the easy way. Differentiate w.r.t. y then w.r.t. x.

However for the question i'm trying to solve I'm given the double integral and have to reverse it, ie fix y and vary x.

It's a good question really - still don't know where to go from here.
5. (Original post by grace_)
Ummm... you could just specify the values of x and y so that you can only get that part of the circle?
I need an expresion of the form .... which isn't easy.
6. I think i've found it.... .

It seems right.
7. (Original post by kexy)
I like how you knew I was finding limits
Not too hard to guess when I remembered the thread from yesterday

It seems right
I think so too, but don't ask me to prove it; I'm having a dumb day!

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