Glancing angle vs deviation angle in X-ray diffraction

[gxc9800]

Homework Statement

in the first photo , the direction of x-ray and the atomic plane are shown.
whereas for the 2nd photo , the
the direction of x-ray and the atomic plane are not shown... so i would assume the glancing angle = 0 . beacuse the atomic plane is parallel to the x-ray ...but in the solution , the glancing angle is 25.25

can someone please draw me a better diagram to show the relationship between the glancing angle( angle betww and deviation angle( deviation of X-ray from the original direction) ...

Homework Equations

The Attempt at a Solution

 

[ehild]

Homework Statement

in the first photo , the direction of x-ray and the atomic plane are shown.
whereas for the 2nd photo , the
the direction of x-ray and the atomic plane are not shown... so i would assume the glancing angle = 0 . beacuse the atomic plane is parallel to the x-ray ...but in the solution , the glancing angle is 25.25

The deviation angle is the angle between the original ray and the reflected ray. Look at the first photo: how are the deviation angle and the glancing angle related?
The second photo shows the deviation angle. From the relation above, what is the glancing angle? Where is the atomic plane?

ehild