Ok for the cylinder dimension, i don't see it, because i use ISO normalization.
So, what mean "n" before the number?
I put the sketch of the first step
For the step2:
Open a new sktech in the middle plan of your volume (face, for me)
Trace construction lines: a vertical one, and an inclined one at 25° (half of 50°)
Add a perpendicular line at 1.327 from the sphere center.
1.327 is obtained by:
2.044 - (0.045 + (0.032 * 21)) = 1.327
(my measures are * 10!)