Return to Mathematics
Euclid's Elements

EUCLIDEAN
GEOMETRY

The study of shape, size, relative position, and the properties of space. It is the language of architects, engineers, and the universe itself.

FIG. 1.0: Structure

The Sum Theorem

Axiomatic Truth

In Euclidean space, the interior angles of any triangle will always sum to exactly 180 degrees (π radians).

The Proof
If L || base,
Alt. Interior Angles are equal.
∴ A + B + C = 180°

Angle Inspector

∠A: 60°∠B: 60°∠C: 60°Σ: 180°
A
B
C
60°
60°
60°
Drag the points to reshape

The Blueprint

The Elements

Axiom

A statement accepted as true without proof. The foundation of the logical system.

Ex: Euclid's 1st Axiom: "A straight line segment can be drawn joining any two points."

Theorem

A statement that has been proven to be true based on axioms and other theorems.

Ex: Pythagorean Theorem: a² + b² = c²

Corollary

A direct consequence of a proven theorem, often easily deduced from it.

Ex: If a triangle is equilateral, it is also equiangular.