Which of the following formulas is not related to triangle geometry?

The formula that is not related to triangle geometry is 2(pi)radius. This formula is actually used to calculate the circumference of a circle, where "pi" represents the mathematical constant approximately equal to 3.14, and "radius" refers to the distance from the center of the circle to any point on its edge.

In contrast, the other formulas directly pertain to triangles. For instance, 0.5 x base x height is the formula used to find the area of a triangle, where “base” is the length of one side of the triangle, and “height” is the perpendicular distance from that base to the opposite vertex. The Pythagorean theorem, expressed as a^2 + b^2 = c^2, relates to right triangles, establishing a fundamental relationship between the lengths of the sides. Thus, the options related to the area of a triangle fundamentally focus on triangle-related calculations, whereas the circumference formula does not apply to triangles at all.