The area used to make the triangular flag is 15 square inches.
Given
Two of the sides are 8 in.
Lila made a triangular flag to cheer on her favorite sports team.
The perimeter of the flag is 20 inches.
<h3>What is Heron’s formula?</h3>
Semi-perimeter is equal to the sum of all three sides of the triangle divided by 2.
Then,
The value of S is;

Therefore,
The area used to make the triangular flag is;

Hence, the area used to make the triangular flag is 15 square inches.
To know more about Heron's formula click the link given below.
brainly.com/question/13907146