ABC is an isosceles triangle with AC = BC. If AB² = 2AC², prove that ABC is a right triangle

Solution:

We know that, in a triangle, if the square of one side is equal to the sum of the squares of the other two sides then the angle opposite the first side is a right angle.

In ΔABC,

It is given that AC = BC and AB² = 2 AC²

⇒ AB² = AC² + AC²

⇒ AB² = AC² + BC² [Since AC = BC]

As the above equation satisfies Pythagoras theorem, we can say that 

⇒ ∠ACB = 90°

Therefore, ΔABC is a right triangle.

☛ Check: NCERT Solutions Class 10 Maths Chapter 6

Video Solution:

ABC is an isosceles triangle with AC = BC. If AB² = 2AC², prove that ABC is a right triangle

NCERT Class 10 Maths Solutions Chapter 6 Exercise 6.5 Question 5

Summary:

If ABC is an isosceles triangle with AC = BC and if AB² = 2AC², it is proved that ABC is a right triangle.

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