Geometric transformations III

What is geometry?

Affine and projective transformation (affinities and projectivities)

Parallel projection of a plane onto a plane. Affine transformations of the plane

Central projection of a plane onto a plane. Projective transformations of a plane

Central projections which carry a circle into a circle. Stereographic projections

Reciprocation (polarity) of the plane. Principle of duality

Projective transformation of a line and a circle. Straightedge construction

Non-Euclidean geometry of Lobachevsky-Bolyai (hyperbolic geometry)

Solutions.