Using parallel line properties and cyclic quadrilateral theorems to find unknown angles.
The set of points that satisfy specific conditions (e.g., a circle is the locus of points equidistant from a center). 2. Classic Problems and Methods Plane-Euclidean-Geometry-Theory-And-Problems-Pdf-Free-47
The starting points, such as "a straight line segment can be drawn joining any two points." Plane-Euclidean-Geometry-Theory-And-Problems-Pdf-Free-47