@salgood@socel.net Hrm... I don't think those are right angles. In all 4 cases, a straight line segment intersects an arc. The only place those intersections would be at 90 deg is infinitesimally close to the intersection. Which is to say, at the intersection itself. Which is to say, on the straight line itself. Which is to say, not an angle, at all.
Now, the tangents of the arcs through the intersection point would, indeed, form a right angle with the intersecting line segment. But with the arcs, themselves? Nope.
This has been an annoying Fediverse reply that takes a joke pedantically seriously. Carry on.