cuk sel tai lujvo

t₁=c₁ is an circle-shaped / circular object.

x₁ is for objects resembling circles, rather than the abstract concept of circles themselves (cuktai). See also tarmi, cukla.

jbovlaste

In notes:

tarmi: x₁ [ideal] is the conceptual shape/form of object/abstraction/manifestation x₂ (object/abstract).
cuktai: t₁=c₁ is a circle.