The perimeter of equilateral triangle is 21m. Find the area. Using Heron's Formula plzzz answer fast i will mark brainliest.

A ≈ 21.22 m²

Step-by-step explanation:

The area (A) of a triangle using Heron's formula is

A =

where s is the semi perimeter and a, b, c the sides of the triangle.

Here the perimeter of the equilateral triangle is 21 m , then

a = b = c = 21 ÷ 3 = 7 m

s = 21 ÷ 2 = 10.5

Then

A =

   =

   =

   ≈ 21.22 m² ( to 2 dec. places )

it has changed from the width and the height.

step-by-step explanation: