One-seventh area triangle¶

The inner triangle formed by three one-third cevians of a triangle, whose area is exactly one seventh of the original.

Version: v1 · 2026-09-08 · History
Domain-specific #: 5870
Origin domain: plane geometry
Subdomain: plane geometry

Core Idea¶

The construction is orientation-sensitive only through cyclic choice and is an instance of Routh-type cevian area formulas; degenerate parent triangles are excluded. Each vertex connects to the point one third along the opposite side in cyclic order, and affine area relations among the resulting small triangles force the central area ratio. The abstraction is therefore identified by a declared carrier, a transformation or constraint over that carrier, and an invariant that tells an analyst whether the named structure is genuinely present.

Scope of Application¶

One-seventh area triangle belongs to plane geometry and is useful where the analyst can specify the typed plane geometry carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets, then evaluate the nondegenerate parent triangle, cyclic side-division convention, three cevians, central intersection triangle and exact one-to-seven area relation are explicit. The scope is broad within that domain but bounded by the need for the nondegenerate parent triangle, cyclic side-division convention, three cevians, central intersection triangle and exact one-to-seven area relation are explicit. The entry records a descriptive analytical identity; practical use requires the governing domain's evidence, standards, and safety obligations.

Clarity¶

The abstraction clarifies a crowded vocabulary by making the nondegenerate parent triangle, cyclic side-division convention, three cevians, central intersection triangle and exact one-to-seven area relation are explicit the center of the account. A claim should name the carrier, the governing operation or relation, the applicable assumptions, and the recognition test. A bare label is insufficient because the name One-seventh area triangle can be used for a formal identity, an implementation, or a neighboring result unless carrier and convention are stated.

Manages Complexity¶

Without the abstraction, an analyst must reason directly over many local details: the carrier roles, admissibility assumptions, competing conventions, derived invariants, boundary cases, and proof or validation obligations specific to One-seventh area triangle. One-seventh area triangle compresses them into the roles in the structural signature. That compression permits comparison across instances without erasing the variables that determine validity. It also exposes which details may be varied safely and which are constitutive.

Abstract Reasoning¶

Identify the carrier. State what the elements, states, objects, or observations are: the typed plane geometry carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets. Reject examples whose alleged carrier belongs to a different problem. 2. Lock the constitutive rule. Express the nondegenerate parent triangle, cyclic side-division convention, three cevians, central intersection triangle and exact one-to-seven area relation are explicit independently of one notation or implementation.

Knowledge Transfer¶

Knowledge transfers strongly among subfields of plane geometry because they reuse the typed plane geometry carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets, Each vertex connects to the point one third along the opposite side in cyclic order, and affine area relations among the resulting small triangles force the central area ratio., and type the carrier, state every parameter and convention in the definition, test that the nondegenerate parent triangle, cyclic side-division convention, three cevians, central intersection triangle and exact one-to-seven area relation are explicit, compare the nearest accepted identity, and report counterexamples, uncertainty, and limiting cases.

Relationships to Other Abstractions¶

Current abstraction One-seventh area triangle Domain-specific

Parents (1) — more general patterns this builds on

One-seventh area triangle is a kind of Ratio Prime

The proposed strict upward parent is prime:ratio.

Hierarchy path (1) — routes to 1 parentless root

One-seventh area triangle → Ratio → Comparison → Self Checking

Neighborhood in Abstraction Space¶

One-seventh area triangle sits in a crowded region of the domain-specific corpus (23^rd percentile for distinctiveness): several abstractions share nearly its structure, so a description that fits it tends to fit its neighbors too.

Family — Convex Geometry & Spatial Partition (35 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-09-08