Step 6: Substitute these values into Heron's formula: Area = √(28 * 21 * 4 * 3).
Step 7: Calculate the product: 28 * 21 = 588, then 588 * 4 = 2352, and finally 2352 * 3 = 7056.
Step 8: Find the square root of 7056 to get the area: Area = √7056 = 84 cm².
Heron's Formula – A method for calculating the area of a triangle when the lengths of all three sides are known.
Semi-perimeter – The semi-perimeter (s) is half the sum of the triangle's side lengths, used in Heron's formula.
Triangle Inequality Theorem – A principle that states the sum of the lengths of any two sides of a triangle must be greater than the length of the third side.