Paper 2 · Geometry Lesson 10 of 19

Geometry 10 – Proof of Theorem 14

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You’ll learn

Prove Pythagoras' theorem (a² + b² = c²) using two pairs of similar triangles
Drop a perpendicular from the right angle to the hypotenuse to split the triangle
Match corresponding sides by their opposite angles using the colour-coding trick
Combine AB² = BC·BD and AC² = BC·DC via BD + DC = BC to finish the proof

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