Classifying Quadrilaterals

Classifying a quadrilateral means collecting its properties, its sides, angles and diagonals, and giving the most exact name they allow. This NSW Year 8 maths subtopic (NESA outcome MA4‑GEO‑C‑01) works with the family of special quadrilaterals: the trapezium, kite, parallelogram, rhombus, rectangle and square.

You will read tick and arrow marks, decide which shapes always have two pairs of parallel sides, tell convex from non-convex shapes, and use co-interior angles adding to \(180^\circ\) to show that sides are parallel. You will also test sides on the number plane with Pythagoras' theorem, find the missing corner of a parallelogram, and decide whether a window frame with unequal diagonals is a true rectangle. It is part of Year 8 Geometry.