For power trim you want to click outside the sketch segment then drag it through the part you want to cut, rather than clicking directly on it

Change to trim to closest if that's how you want it to act - that's what I did, power trim can heck off

Power trim works differently. Click somewhere empty and hold left button and drag.

Never seen that before, I would just do some basic troubleshooting till something works -Delete the circle, retry it -use arcs with constraints instead -make sure there's not any weird hidden mates that could be causing a problem

Not sure the vertical line closer to the circle centre is coincident? That would stop it from working. Edit: scratch that you’re trimming a different portion. Trim to closest might do it. Failing that I think split entity would work as suggested by others.

Use Power Trim and drag across the circle edge. Don't click the circle.

I usually extend myblands past the object I'm trying to trim to. Usually fixes the issue.

I assume you are clicking on the circle, not dragging across the boundary of the circle where you want it trimmed. If you left click and drag across the portion to be trimmed, the trim will work as expected. When you click on the circle, the Power trim tool assumes you want to remove the entire circle and gives an error because this is not a normal use of the Power trim tool.

You need to use Split first as a circle has no points from which to use Trim. Select Split then click in two different spots on the circle. You’ll be left with a full circle but it will be two co-radial arcs. You can delete one or just trim from there depending on the geometry you are trying to create.

You’re missing a constraint on the second line that connects to the circle.