In this paper, we introduce two new geometric constants related to the heights of triangles: ΔH(X) and Δh(X,I). We also propose two new geometric constants, Δm(X) and Δm(X), related to the midlines of equilateral triangles, and discuss the relation between the heights and midlines in equilateral triangles. We give estimates for these geometric constants in terms of other geometric parameters, and the geometric constants are used to discuss geometric properties such as uniform non-squareness, uniform normal structure, and the fixed point property.

Keywords: uniform non-squareness, uniform normal structure, fixed point property