Triangle has a 4cm ,7cm and 9cm long.whats is its area correct to one decimal place?

To find the area of a triangle with side lengths of 4cm, 7cm, and 9cm, we can use Heron's formula:

s = (a + b + c) / 2
s = (4 + 7 + 9) / 2
s = 10

Area = √[s(s - a)(s - b)(s - c)]
Area = √[10(10 - 4)(10 - 7)(10 - 9)]
Area = √[10(6)(3)(1)]
Area = √[180]
Area ≈ 13.4 cm²

Therefore, the area of the triangle is approximately 13.4 cm².

Step 1: Calculate the Semi-perimeter

s = (4 cm + 7 cm + 9 cm) / 2
s = 10 cm

Step 2: Use Heron's Formula

Area = √(s(s - a)(s - b)(s - c))

where a, b, and c are the lengths of the three sides.

Area = √(10 cm(10 cm - 4 cm)(10 cm - 7 cm)(10 cm - 9 cm))
Area ≈ √(10 cm x 6 cm x 3 cm x 1 cm)
Area ≈ √180 cm²

Step 3: Round to One Decimal Place

Area ≈ 13.4 cm²

Therefore, the area of the triangle, correct to one decimal place, is 13.4 cm².