Those brackets don't care one iota what angle your boards meet at. They're simply a shear connection. The problem you'll encounter is that they'll be too short. Some ideas for that:

- **Nip the toe off your railings** to a height of 3½" (to match the height of a square cut). A little sanding to match the eased edge on the rest of the board and you're good. The level top height should match that of your horizontal rails for best appearance. 

- **Use _two_ brackets**. Cut one end off of each such that you arrive at a total length appropriate for the length of the angled rail cut. Drill extra fastener holes if needed. 

In either case the lower post screw will be a challenge. Angle it upward and consider using a long, flexible bit driver. 

That said, I'm not a fan of this kind of hardware. I consider it a crutch to good carpentry, and it doesn't look that great. It leaves gaps and metal showing. I would carefully drill and **countersink three toenails** on the less-visible side of your rails and go with that. 

Or, **use a wooden rosette** in the same way you're using these brackets. You can by some 1x4 or split a bit of 2x4 down to 3/4" thickness and mount it to the rail, then screw it to the post. Actually, I'd replace the brackets with these across the board (so to speak). They'd look a bit better in my humble opinion. 

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Good work! Congrats on accepting the challenge to DIY. Here are a few other tips for now or future projects:

- Leave your posts a bit higher than the top rail. Flush joints usually don't look great, and then you can bevel the post tops for visual interest. At this point you could cap your post with an oversized square two-by with beveled corners or top edges.  

- Bevel the corners of your flat top rail so they meet the posts a bit more nicely. The final width should be about 3" so you don't hit the rounded post corner. 

- Partially or completely bevel the bottoms of your balusters so they visually blend with the bottom rail a bit better and aren't as hazardous to ankles. 

- Countersink for the bracket-to-rail screw heads in your posts to avoid the gap they create, or use flathead screws and countersink the brackets.