Pi

Explanation

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Answer: 62.5

In used a ruler to measure exactly the lengths of the triangle's sides. I split the figure into 4 triangles "B-E-D, A-B-C, B-D-C, and F-D-C. I found the area of the triangles with the formula 1/2 BxH. ABC:10.5 BED:14 BDC:17 FDC:21. 

I found the lengths of the triangle sides then multiplied them "4 x 8 = 36" Then I divided it by 2 "36 divided by 2 = 18" So 18 would be the area of the triangle. Then I added the area of all 4 of the triangles and got the answer.