Full Idea
That 'all and only equilateral triangles are equiangular' required proof, and not for mere curiosity, is grounds for thinking that being an equilateral triangle is not the same property as being an equiangular triangle.
Gist of Idea
Equilateral and equiangular aren't the same, as we have to prove their connection
Source
Scott Shalkowski (Essence and Being [2008], 'Serious')
Book Reference
'Being: Developments in Contemporary Metaphysics', ed/tr. Le Poidevin,R [CUP 2008], p.53
A Reaction
If you start with equiangularity, does equilateralness then require proof? This famous example is of two concepts which seem to be coextensional, but seem to have a different intension. Does a dependence relation drive a wedge between them?