On Sun, 15 Aug 2004 09:54:29 -0400, "J. Clarke"
wrote:

Why? The support posts are vertical and each the same height, and
those the same height as the ones holding the horizontal deck railing.
Since there is at least one post at the top and at the bottom, the
rail must wind up parallel [same angle] to the stairs.

Read the thread title. The OP did not ask whether she needed to know the
angle, she asked how to find out what it was.

Read the reply. It's better to give stronger advice than to answer a
questionable question. She can find the angle by trig as well, but I
wouldn't advise that either. The point is that there is no need to
measure the angle, and it does little good. A better way is simply a
better way. Any angle [stair to post] can be copied using an
adjustable bevel if necessary.

Bill.