Calibration of an ellipse's algebraic equation and direct determination of its parameters.
Certain equalities and inequalities concerning polygons in .
Certain inequalities concerning some kinds of chordal polygons.
Ceva's and Menelaus' theorems for the -dimensional space.
Cevians as sides of triangles.
Circumcenter, Circumcircle and Centroid of a Triangle
We introduce, using the Mizar system [1], some basic concepts of Euclidean geometry: the half length and the midpoint of a segment, the perpendicular bisector of a segment, the medians (the cevians that join the vertices of a triangle to the midpoints of the opposite sides) of a triangle. We prove the existence and uniqueness of the circumcenter of a triangle (the intersection of the three perpendicular bisectors of the sides of the triangle). The extended law of sines and the formula of the radius...
Classes of Graphs Which Approximate the Complete Euclidean Graph.
Counting all equilateral triangles in .
Cutting circles and the Morley theorem.
Cyclic quadrangles from squares.
Cyklografie [Book]
Cylinder and horoball packing in hyperbolic space.