Ex 6.6 Q6
Question Prove that the sum of the squares of the diagonals of parallelogram is equal to the sum of the squares of its sides.
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CBSE Class 10 Triangles — Complete Guide
Triangles carries the highest marks in Geometry (8-10 marks). BPT proof and Pythagoras theorem proof are must-prepare topics.
Quick Revision: Key Concepts
- BPT: If DE ∥ BC, then AD/DB = AE/EC
- Similarity criteria: AA, SSS, SAS
- Area ratio: ar(▵1)/ar(▵2) = (side ratio)²
- Pythagoras: hypotenuse² = base² + perpendicular²
Most Important Questions
- Prove BPT (Thales' theorem) — 5 marks guaranteed
- Prove Pythagoras theorem using similarity
- Prove triangles are similar using AA/SSS/SAS and find unknown sides
- Area ratio problems
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