Lila made a triangular flag to cheer on her favorite sports team. The perimeter of the flag is 20 inches.

A triangular flag is shown. 2 sides have lengths of 8 inches. The total perimeter of the flag is 20 inches.

Heron’s formula: Area = StartRoot s (s minus a) (s minus b) (s minus c) EndRoot

Approximately how many square inches of fabric were used to make the triangular flag?

15 square inches
76 square inches
186 square inches
215 square inches

Step-by-step explanation:

Lila made a triangular flag to cheer on her favorite sports team. The perimeter of the flag is 20 inches.

A triangular flag is shown. 2 sides have lengths of 8 inches. The total perimeter of the flag is 20 inches.

Heron’s formula: Area = StartRoot s (s minus a) (s minus b) (s minus c) EndRoot

Approximately how many square inches of fabric were used to make the triangular flag?  

15 square inches

76 square inches

186 square inches

215 square inches

Given that we have an outside border of 20 inches and 2 sides are 8 inches each, the third side is equal to 4 inches. Solving for s which is the semi outside border ,                                                   S = 20/2 = 10

Using Heron’s formula,

A = sqrt of  (10)(10-8)(10-8)(10-4) = 15.49 in2

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