In an isosceles triangle ABC, if AB = AC = 26 cm and BC = 20 cm, find the area of triangle ABC.

Question

Question

This question was previously asked in

NTPC CBT-I (Held On: 4 Jan 2021 Shift 2)

Answer 1

Given:

In an isosceles triangle ABC,

AB = AC = 26 cm and BC = 20 cm.

Calculations:

F1 Ashish Ravi 25.10.21 D1

In this triangle ABC,

∆ADC = 90° ( Angle formed by a line from opposite vertex to unequal side at mid point in isosceles triangle is 90°)

So,

AD² + BD² = AB² (by pythagoras theorem)

⇒ AD² = 576

⇒ AD = 24

Area of triangle = ½(base × height)

⇒ ½(20 × 24) (Area of triangle = (1/2) base × height)

⇒ 240 cm²

∴ The correct choice is option 2.

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