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# Interesting trig problem my teacher solved. Can't remember how he did it now... watch

1. Why does arctan(1/3) have the same decimal places as arctan(2)?

18 and 63 respectively...

.43494882..

I see no symmetry?
2. I take it you're using degrees here.

Let and . Then and . Then we can apply the angle addition formula:

So what is (in degrees)? So why do they have the same stuff after the decimal point?
3. You can try
1/2,3
1/4,5/3
1/5,3/2
etc. too.
4. (Original post by nuodai)
I take it you're using degrees here.

Let and . Then and . Then we can apply the angle addition formula:

So what is (in degrees)? So why do they have the same stuff after the decimal point?
I see! I knew it was some addition formula of some kind, thanks for that, got it now!

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Updated: April 8, 2011
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