We survey elementary results in Minkowski spaces (i.e. finite dimensional Banach spaces) that deserve to be collected together, and give simple proofs for some of them. We place special emphasis on planar results. Many of these results have often been rediscovered as lemmas to other results. In Part I we cover the following topics: The triangle inequality and consequences such as the monotonicity lemma, geometric characterizations of strict convexity, normality (Birkhoff orthogonality), conjugate diameters and Radon curves, equilateral triangles and the affine regular hexagon construction, equilateral sets, circles: intersection, circumscribed, characterizations, circumference and area, inscribed equilateral polygons.
Martini, H., Swanepoel, K. J., & Weiß, G. (2001). The geometry of Minkowski spaces — A survey. Part I. Expositiones Mathematicae, 19(2), 97–142. https://doi.org/10.1016/s0723-0869(01)80025-6