Wah Yan · Secondary Mathematics

Centres of a Triangle

Special lines in a triangle — angle bisectors, perpendicular bisectors, medians and altitudes — and the four centres they determine: the incentre, circumcentre, centroid and orthocentre.

The junior secondary part follows Junior Secondary Mathematics in Action 3A, Chapter 6, including every green core-concept card and its proof. The senior secondary part covers coordinate methods for the four centres, Euler’s line, and a few clearly marked Out-of-Syllabus formulas.

F3 · Chapter 6

初中 Junior Secondary

Definitions, properties and proofs, positions of the four centres, and the 四心經 memory chant.

DSE · Coordinate geometry

高中 Senior Secondary

Euler’s line and coordinate methods for H, G, O and I. Out-of-Syllabus formulas are clearly marked.