“The triangle, circle, square…” is a phrase I have encountered in a few martial arts. In Aikido, it captures entering (piercing like the point of a triangle), redirecting (circle) and grounding (like the stable base of a square); in kung-fu it relates to heavenly principles of nature which guide motion (square), relying on the grounding of the Earth as a source of power (circle) and training and conditioning the body and mind of the person as a channel between both (triangle).
Everything has a shape, takes up space, and moves with direction and velocity. The question is what is that geometry used for? Martial arts often have the short-term goal of winning the battle and the long-term goal of ending the conflict. This is not complete and a little simplistic, but it often seems like short-term goals of “winning” a fight relies on understanding the internal geometry of the body and the long-term goals of reducing or ending the conflict relies on understanding external geometry of one person’s position relative to another.