Are you telling me that you didn't fully grasp Into the Night's example of "trigonometry" as an entire branch of mathematics that applies the Pythagorean theorem to a circle as an example of the Pythagorean Theorem being applied to a circle, and that my additional example and clarification wasn't of any help either?
I can. I suppose you didn't like my example. Do you recognize any terms on this list? Sine, Cosine, Tangent, Cotangent, Secant, Cosecant, Arcsine, Arccosine, Arctangent, Arc cotangent, Arc secant, Arc cosecant ... They are all defined via the relationship between angles of a circle and the right triangles thusly formed. The right triangles enable the Pythagorean theorem to be applied to establish the circle's radius. Why does this not count?
If I use the Pythagorean theorem to determine the radius of a circle, how would that be an incorrect application?
As I have mentioned elsewhere, you have to show the error in the application. You don't get to just claim it. Get to it.