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. 

- **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. 

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 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. They'd look much better. 

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Good work! Congrats on taking 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. 

- 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.