Since you will only need two steps to reach your 21" high deck, you might
consider "stacked boxes" instead of the usual stair stringers. *While I
normally cut stair stringers for longer stairs, I used the box approach
for the front and back steps of our house. Easy to build, and rock solid.


That did the trick...simple and solid. The concrete pavers that the
'box' rests on weren't completely level, so I shimmed it with narrow
strips cut from spare shingles.

I avoided the angle measurement problem, but I'm sure it will crop up
again in the near future.