Re: Question in Geometry

On Sep 24, 4:05 pm, riderofgiraffes <mathforum.org...@xxxxxxxxxxxxxx>
wrote:
Miki - you're not providing any evidence to use that
you are thinking about this at all.  You don't seem
to be bothering to work things out given what you've
been told.

... V1 is of the form [a, 0, 0] where a > 0.

Good.  So what is the normalised form of V1?
What does it mean to be normalised?  Can you
find a vector of length 1 that points in the
same direction as V1?

I also think that the angles between V1 and
V2 is independent of their length,

Correct.

I dont know how to calculate the angle given
only phi and theta and V2.

You've been told that already.  Check again,
and check carefully.  Then if you still have
a problem, tell us what you've tried.

You might also tell us where the problem comes
from so we can better help you understand the
stuff that actually matters.

Alright then, let me rephraise the problem because I think that I had
made a mistake.

Well, take any vector V1 (in 3D) that is localised somewhere in the XY
plane. In contrast to I wrote ealier, I dont know anything else about
V1 besides this fact.
Consider the vector V2 with the following properties:
1. The angle between V2 and its projection on the XY is Beta.
2 The angle between its projection and the vector V1 is Alpha

Now, what is the angle between V1 and V2 where all I know is:
Alpha, Beta and V2.

Thanks,
Miki
.

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