masking inner part of circle

[basilic]

From the screenshot and the Designer files attached, I'd like to achieve a sort of masking between a triangle and an empty circle with a large stroke: I'd like to mask the part of triangle that crosses over the circle.

I managed to do it on the top drawing but only by applying a white fill in the circle. Which isn't smart, is it?

I'd like to keep the transparency. So, how do I do that from the bottom drawing?

tri-cir.afdesign

[dutchshader]

you could place a ellips above the ellips and triangle and set it to erase.

tri-cir.afdesign

Edit: misread your post @Alfred way would do the trick

[Alfred]

1. Duplicate the circle

2. Remove the white fill from the new (top) copy

3. Select the original circle layer and set its blend mode to ‘Erase’

[basilic]

Thanks to both of you for the speedy answer!