1. Given that : AB² = 2AC² ⇒ AB² = AC² + AC² ⇒ AB² = AC² + AB² [Because AC = BC] These sides satisfy the pythagoras theorem. Hence, the triangle ABC is a right angled triangle.

    Given that : AB² = 2AC²
    ⇒ AB² = AC² + AC²
    ⇒ AB² = AC² + AB² [Because AC = BC]
    These sides satisfy the pythagoras theorem.
    Hence, the triangle ABC is a right angled triangle.

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  2. Let ABC, be any equilateral triangle with each sides of lenght 2a. Perpendicular AD is drawn from A to BC. We know that the altitude in equilateral triangle, bisects the opposite sides. Therefore, ∴ BD = DC = a In triangleADB, by Pythagoras theorem AB² = AD² + BD² ⇒ (2a)² = AD² + a² [Because AB = 2aRead more

    Let ABC, be any equilateral triangle with each sides of lenght 2a. Perpendicular AD is drawn from A to BC.
    We know that the altitude in equilateral triangle, bisects the opposite sides.
    Therefore, ∴ BD = DC = a
    In triangleADB, by Pythagoras theorem
    AB² = AD² + BD²
    ⇒ (2a)² = AD² + a² [Because AB = 2a]
    ⇒ 4a² = AD² + a²
    ⇒ AD² = 3a²
    ⇒ AD = √3a
    Hence, the lenght of each altitude is √3a.

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