Question

The sides of a triangle measures 13 cm, 14 cm and 15 cm. Its area is

(a) 84 cm² (b) 91 cm² (c) 168 cm² (d) 182 cm²

Answer 1

(a) 84 cm²

Because,

Let a, b, c be the sides of the triangle

Then, s = (1/2) (a + b + c)

= (1/2) × (13 + 14 + 15)

= (42/2)

= 21

Area of triangle = √(s(s-a) × (s-b) × (s-c))

= √(21 × (21 – 13) × (21 – 14) × (21 – 15))

= √(21 × (8) × (7) × (6))

= √(3 × 7 × 2 × 2 × 2 × 7 × 2 × 3)

= √(3² × 7² × 2² × 2²)

By cancelling square and square root we get,

= (3 × 7 × 2 × 2)

= 84 cm²