Chapter 7: Coordinate Geometry

Coordinate Geometry covers the distance formula, the section formula (a point dividing a segment in a given ratio), a triangle's area from its vertices' coordinates, and a line's slope. The distance between (0,0) and (3,4) works out to √(3²+4²)=5 — the same 3-4-5 triangle from the Pythagorean theorem, just placed on a coordinate grid.

Applying the section formula with the ratio the wrong way round silently reverses which point the answer ends up closer to — worth checking every time. This chapter turns Class 9's introductory coordinate plane into a genuine problem-solving tool, translating geometric questions straight into algebra.