Use the knife project operator.
Take your object you want to slice.
Then add another circle mesh that has as many verts as you want slices.
Rotate it into position, push
F to fill it, and then
F3 to search for
Poke faces to get it separated into smaller triangles.
You can also do all of this when you add the circle in the first place, in the Add Circle options. It's useful to know this method too.
Then go into edit mode and search for "Delete Faces Only" which does just that, leaving only edges behind.
Here's where it gets tricky.
- Select the object you want sliced.
- In edit mode select the geo you want to receive the cut.
CTRL + Click the "cutter mesh" while still in edit mode on the main object. You'll see it turn red.
Then swing into front orthographic view,
Search for "Knife Project" and shoot.
If you did everything right you should have exactly what you're looking for. The edges of the cutter mesh shoot out onto the surface of the main object. Pretty nifty.
It's okay if you have to try like 6 times. Honestly i think I can count the amount of times I've done it 100% correct on the first go on one hand.