Are 3D coordinate angles restricted to certain values?

[Tiven white]

Homework Statement

In 3d coordinate space any two of the coordinate angles must
A. Sum to less than one
B. Be greater than ninety but less than one eighty.
C. Each be greater than forty five degrees
D. Sum to greater than 90 ( if they are both less than 90)
E. Have cosines less than (√2/2).

Homework Equations

The Attempt at a Solution

I think the answer is e but there is s some conflict between c can anyone clear this up for me

 

[voko]

What is your reasoning for C and E?

 

[Tiven white]

The squared cosine of all the three angles = to 1

 

[vanhees71]

I must say, I don't even understand the question. What's meant by the "coordinate angles" here? If you refer to spherical coordinates in 3 dimensions, then the polar angle is between $]0,\pi[$ and $\pi$ and the azimuthal angle between $[0,2 \pi$. This is a chart for the entire Euclidean space except the polar axis.

 

[voko]

The squared cosine of all the three angles = to 1

And how does that imply C or E?