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Chapter 7 Class 9 Triangles

Serial order wise

Last updated at May 29, 2018 by Teachoo

Given: AD is bisector of ∠ A So, ∠ BAD = ∠ CAD Also, AD is perpendicular to BC So, ∠ ADB = ∠ ADC = 90° To prove: AB = AC & Δ ABC is isosceles Proof: In ΔABD and ΔACD, ∠ BAD = ∠ CAD AD = AD ∠ ADB = ∠ ADC So, Δ ABD ≅ Δ ACD So, AB = AC Since 2 sides of triangle are equal Δ ABC is an isosceles triangle