How to find the area of a triangle with 3 sides given as a = 4, b = 7, and c = 9.

A triangle is a closed figure or shape with 3 sides, 3 angles, and 3 vertices.

Answer: The area of a triangle with 3 sides is 13.41 units

Let's find the area of a triangle using Heron's formula.

Explanation: 

The semi-perimeter is: 

s = (a + b + c) / 2

= (4 + 7 + 9) / 2

= 10

We will find the area of the triangle using the Heron's formula.

A = √[s (s - a) (s - b) (s - c)]

= √[10 (10 - 4) (10 - 7) (10 - 9)]

= √10 × 6 × 3 × 1

= √180

≈ 13.41

Thus, the area of a triangle with 3 sides is 13.41 units