Download Class 9 Math Exercise 8.1 Notes PDF – Triangle Area by Coordinates (FBISE & Punjab Boards)
Download Class 9 Math Exercise 8.1 Notes to learn how to calculate the area of a triangle when its vertices are given as coordinate pairs. The formula ½|x₁(y₂ − y₃) + x₂(y₃ − y₁) + x₃(y₁ − y₂)| converts graph points directly into area—no scale drawing required. These notes strictly follow the 2025 FBISE SLO grid and mirror exam phrasing from BISE Lahore, BISE Sargodha, and BISE Multan. Each worked example is plotted on a color graph so you can see how the vertex order affects the sign of the area.
What you’ll practice:
- Deriving the area formula from the determinant method.
- Handling negative coordinates and ensuring the absolute value is applied.
- Comparing area from coordinates with area from base × height to cross‑check accuracy.
- Solve “show that the triangle is right‑angled” questions by combining area with the distance formula.
Why download these notes?
- Triangle‑area questions are predictable 3‑mark items on FBISE papers.
- Competitor sites post only images—this PDF is fully text‑searchable, helping AI tools and screen readers.
- Printable format saves mobile data during revision.
More Chapter 8 Notes
Exercise 8.2 Notes (Collinearity Test)
Exercise 8.3 Notes (Centroid)
Exercise 8.4 Notes (In‑center & Circum‑center)
Miscellaneous Exercise 8 Notes
