Question

find the area of an isosceles triangle whose sides measure 13 cm and the base is 20 CM​

Answer 1

Let:-

The vertices of the given isosceles triangle be ABC respectively.

As it is an isosceles triangle, so two sides AB = AC = 13 cm

Length of the base BC = 20 cm

Construction:-

Draw perpendicular AD .

In triangle ADB,

BD = 10cm (As D is mid point of BC)

AB = 13 cm

AD² + BD² = AB² (Using Pythagoras theorem)

AD² + 10² = 13²

AD² = 13² - 10² = 8.3 cm

So:-

Area of triangle ABC = 1/2 × 20 × 8.3 cm²

Area of triangle ABC = 83 cm².

Therefore:-

Area of the triangle is 83 cm².