Chapter 3: Construction of Quadrilaterals

Construction of Quadrilaterals is the one Class 8 chapter judged on a drawing, not a number — using ruler and compass to build a quadrilateral accurately from a limited set of measurements, such as four sides and a diagonal, or three sides and two angles. Each method takes its name from exactly what's given: SSSSA (four sides and one angle), SASAS (side-angle-side-angle-side), and so on.

Skipping a rough sketch before starting the accurate drawing is what usually wastes an attempt — without labelling what's actually given first, it's easy to build a quadrilateral that doesn't match the problem at all. A rough sketch also reveals early whether the given measurements can even form a valid quadrilateral, before any compass work begins. The spatial reasoning built here also feeds directly into Class 9's formal geometric constructions.