Equation of circle with arc length

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Grand
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Homework Statement


Equation of a circle is:
[tex]x^2+(y+a)^2=R^2[/tex]

x intercepts are [tex]+/-\sqrt{3}[/tex] and arclength above x-axis is [tex]\frac{4\pi}{3}[/tex]

Find a and R.
 
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Welcome to PF!

Hi Grand! Welcome to PF!

(have a square-root: √ and a pi: π and try using the X2 icon just above the Reply box :wink:)

Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
 
Hello, I've been tackling the problem for a while and the equation that I managed to come up with is:
[tex]\arcsin{\frac{\sqrt{3}}{R}}=\frac{4\pi/3}{2R}[/tex]

I can't solve it, and haven't found anything else useful.
 
Hello Grand! :smile:

Yes, that looks good …

but it's obviously unsolvable without a computer, sooo :rolleyes:

hadn't you better assume the answer is really obvious, and just make a guess and see if it's right? :biggrin:
 
Well, is it? Even though it is stated in the book, I want to find a way to actually obtain it. Is there a way?
 
hmm :rolleyes: … computer, Newtonian approximation, bribing the TA … :wink:
 
Taylor was my guess too, but here we aim at an exact answer, so we should not use it. Even though, how would you guess the answer?
 
uhhh? :confused:

how many angles do you know with "√3" in the sine ? :smile:
 
Yeah, alright. But come on, there must be some rigorous way doing it - I've been solving it for couple of hrs now, even managed to prove Pythagoras with it.
 
What's wrong with guess-and-check? It's a valid method. I don't mean to put you down, but combining this method with drawing a diagram, I was able to get the answer within minutes.