Question

The area of an isosceles triangle whose equal sides are 5 cm each and base is 8 cm, is ______.

Options

• 12 cm²

• 18 cm²

• 6 cm²

• 9 cm²

Answer 1

The area of an isosceles triangle whose equal sides are 5 cm each and base is 8 cm, is 12 cm².

Explanation:

Given: Equal sides b = 5 cm, base a = 8 cm.

Step-wise calculation:

Use formula for area of an isosceles triangle: 

Area = `a/4 xx sqrt(4b^2 - a^2)`

1. Compute inside the square root:

4b² – a²

= 4 × (5)² – 8² 

= 100 – 64

= 36

2. `sqrt(36) = 6`

3. Area = `8/4 xx 6`

= 2 × 6

= 12 cm²

The area is 12 cm².