2D geometry

Plane geometry lets you describe points and lines with numbers: where they are, how far apart they are, how steep a line is and how lines intersect. In this topic you work with the coordinate system, the distance between two points and the midpoint, the gradient and the equations of a line, parallel and perpendicular lines, the distance from a point to a line and perpendicular bisectors, and you finish with Voronoi diagrams, a very typical tool in Applications and Interpretation for deciding which area is closest to each point (shops, masts, hospitals). In the exam, almost everything is done with the graphic display calculator (GDC) and a diagram, so it is worth practising drawing a sketch before you calculate.

Recommended order

Work through the sections in order: section 1 gives the basic tools (distance and midpoint), section 2 is the heart of the topic (gradient and equations of a line), sections 3 and 4 use the gradient for parallelism, perpendicularity and distances, and section 5 applies everything to Voronoi diagrams. At the end you will find IB exam questions grouped by type.