All themes/Mathematics/Plane Geometry/ Help Introduction. Movie Tangram The Point, the Straight Line. Movie The Angle. Movie Parallels. Movie Triangle. Movie Triangle Solution of triangles. Movie Pythagorean Theorem Solution of a triangle. Problem 1 Solution of a triangle. Problem 2 Solution of a triangle. Problem 3 Circle. Movie Quadrilateral. Movie The Trapezoid The Quadrilateral Inscribed and Circumscribed Quadrilaterals Figures Constructing. Movie Segment bisecting Segment bisecting. Movie Drawing a perpendicular to a given straight line Drawing a perpendicular to a given straight line. Movie Construction of a triangle by its three sides Construction of a triangle by its three sides. Movie Construction of an angle equal to a given one Construction of an angle equal to a given one. Movie Construction of an angle bisector Construction of an angle bisector. Movie Construction of a parallel to a given straignt line Construction of a parallel to a given straignt line. Movie Dividing of a segment into n equal parts. Movie Construction of the fourth proportional segment. Movie Polygon. Movie Cartesian coordinates. Movie Vectors. Movie Transformations. Movie Symmetry Area. Movie Measuring of Areas