2. Polynomials
3. Geometry
6. Mensuration
6.1. Measurement of Areas
6.1.1. Measuring Areas of Triangles
6.1.2.1. Area of a Quadrilateral
6.1.2.2. Area of a Parallelogram
6.1.2.3. Area of a Rhombus
6.1.2.4. Area of a Trapezium
Grade 9 Hong Kong School Math Application of Results on Area of Polygonal Regions
Master this topic as part of Measuring Areas of Quadrilaterals