# Component velocity vector

#### dirk_mec1

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#### Päällikkö

Homework Helper

Use the Pythagorean theorem, sin2x + cos2x = 1, repeatedly.

#### dirk_mec1

I don't know how to start.

Use the Pythagorean theorem, sin2x + cos2x = 1, repeatedly.
Yes, I figured that out from (5) but the main thing is I don't know understand as to where pythagoras needs to be used.

First of all U0 is parallel to x-axis, right? (I image a x-as to the right y axis out of the picture and z up).

#### Päällikkö

Homework Helper
Well, I suppose you could do the problem geometrically, but I just crunched through the algebra.
cos2a + sin2a sin2b = cos2b + (1 - cos2a) sin2b ...
Write it out, apply the Pythagorean theorem again, regroup, Pythagorean theorem, etc.

Hope this helps?

#### dirk_mec1

Well, I suppose you could do the problem geometrically, but I just crunched through the algebra.
cos2a + sin2a sin2b = cos2b + (1 - cos2a) sin2b ...
Write it out, apply the Pythagorean theorem again, regroup, Pythagorean theorem, etc.

Hope this helps?
I understand the equality but its the geometry that gives the problem, I want to know where (5) comes from!

#### dirk_mec1

It suprises me no one was able to help with this, from what I thought was a simple geometry, problem. Anyway I figured out myself. It turns out that you'll have to give the bar a length say L and then express each the length of the sides in alpha and beta.

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