Help with a miter cut

Hello. Am making a deck and getting hung up on geometry and woodcutting.
The way the stairs are going, I have to have two pieces of wood at a 130 degree angle from each other
******* ******** ******** *****B** A ********************* ********************* I tried to depict it above. What manner of power tool does one use to cut the slanted board coming down? The edge (B) is cut beyond 45 degree which is what my skil saw and my miter saw go to. Miter box is same way. Hand saw sucks for this (These are 2" x 8" deck boards), because I can't cut it straight enough. Bottom line question: how do I cut an angle greater than 45 degrees??
Thanks in advance for any help.
John
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

*********************
*********************
is
If you cannot pull this off with a hand saw, or by using a circular saw "free hand," try clamping a straight edge to the stair stringer and run the edge of the circular saw's shoe against it.
On another note, a 2X8 sounds awfully small for a stair stringer... typically 2X12s are used. Or are you simply nailing cleats on the stringers rather than cutting 'saw tooth' stringers?
Perhaps you could simply purchase precut PT stringers at Home Depot? Might save you some angst laying out and cutting the stringers... I've built quite a number of stairs over the years so it was worth the angst on the first set. If you don't think you will ever make another set of stairs the angst may not be worth the experience, particularly if the overall rise is close enough to the available stringers to result in step rises at the top and bottom that are roughly the same at the other steps'.
John
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

I always use a hand-held circular saw and a straight edge.

If we're talking about the stringer for the steps, use 2x12.
BTW, steps are very complicated to lay out. Mistakes happen easily. I have found it wise to use a piece of scrap plywood or particleboard or something similar to cut a prototype of the stringer and set it next to the deck to see that it fits the way I want it to. It constantly amazes me the multitude of ways one can make a mistake on this.
Good luck.
Peter