Three lines can meet at angles of 120 degrees {isometric axes}.
Lines can intersect coordinate planes at one point {piercing point}, where they orthogonally project onto coordinate planes. Surfaces intersect coordinate planes to make curves {trace curve}.
Four symmetry axes {quartic symmetry} can make eight angles of 45 degrees.
A line {transversal} can cross two coplanar lines, to form four angle pairs. Angles can orient in same direction {corresponding angle, transversal}. Angles {alternate angle} can lie on opposite sides of coplanar-line transversal. Angles can be opposite each other at intersection points {vertically opposite angle}.
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Date Modified: 2022.0225