# The surface of a unit sphere

1. Mar 3, 2009

### Micle

Please help, I have an assignment's question but I don't idea how to work on it. The question is that:

Let R be a unit random vector points on the surface of a unit sphere. If the probabilty of R is uniform over the entire surface of a unit sphere, find the pdf of the projection of R on the x-axis

any idea to do so?

2. Mar 4, 2009

### lanedance

Hi Micle

so in this example area/total sphere area is probability to find your vector within the given area

so the probability of having a projection will be related to the area area/total sphere area for a given dx incremnent at that position

3. Mar 9, 2009

Hi Lanedance

Thanks!

4. Mar 9, 2009

cheers