Ostensibilities in geometry play a large role and are a little shined in literature. Their presence at geometry is much broader, than it actually is perceived. Work explains a status of ostensibilities in geometry and proves that geometry becomes the closed rule only taking into account its ostensibilities. A new way related to creation of two circles’ radical axis and two conics’ chordal straight lines based on machine graphics tool «Central Proportional Increase of Graphic Object» is offered. The way allows select ruled degenerations from a bunch of quadrics.
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Гирш et al. (2014) studied this question.