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I have a ball. I know its azimuth and speed. I want to count the azimuth after a bounce (wall probably). Lets call the azimuth alpha. Image:

angle

I know the alpha. I know the wall azimuth. I need "?". Beta would be nice (but not so necesary).

Zaheer Ahmed
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noisy cat
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1 Answers1

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The ? is 360-alpha (in degrees).

This is because beta = alpha.

Oliver Charlesworth
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  • i thought beta == alpha but i wasnt sure :P what to do with horizontal wall? – noisy cat Mar 08 '12 at 18:51
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    @kittyPL Why the fact that the wall is horizontal should change geometry? – Manlio Mar 08 '12 at 18:51
  • @Saphrosit I think it would change something... Becouse If I bounce by the horizontal wall, it cant be 360-alpha... – noisy cat Mar 08 '12 at 18:53
  • @kittyPL: If the wall is at an angle of `gamma`, then the final direction will be `2*gamma - alpha`. – Oliver Charlesworth Mar 08 '12 at 18:55
  • @kittyPL: A horizontal wall won't change anything, because you're measuring alpha relative to the wall. When you turn the wall, the *relative* angles don't change, but if you need absolute angles (e.g., compared to straight up) you'll need to add the angle of the wall to the relative angle to get an absolute angle. – Jerry Coffin Mar 08 '12 at 18:56
  • @OliCharlesworth you r my god :) thanxxx much – noisy cat Mar 08 '12 at 19:01