Geometry here is about the measurements that come from a shape's dimensions: an angle, a length, an area, a volume. Every calculator in this subsection takes sides, radii or angles you already have and returns a measurement about the shape those figures describe, which is a narrower job than algebra's — nothing here solves for an unknown embedded in an equation; the numbers you enter are exactly the measurements a shape actually has.
Calculators in this section
Triangles account for most of what is here, and for good reason: the Pythagorean theorem (a² + b² = c², used for the hypotenuse) and the rule that a triangle's interior angles always sum to 180° are two of the few genuinely load-bearing facts in practical geometry, showing up in construction, navigation and design far more often than the more exotic shape formulas taught alongside them. Circles and cylinders extend the same idea into curves and three dimensions — a circle's circumference from its radius, a cylinder's volume from its radius and height — while quadrilateral area covers the four-sided shapes that do not reduce neatly to a triangle.
What is deliberately absent is coordinate geometry and trigonometric identities beyond the triangle basics — this subsection sticks to the measurements someone with a tape measure and a protractor, rather than a graphing calculator, actually needs.