Applying the trigonometric area formula, the amount of fabric she will need to make all the three triangles is: C. 417 square inches.
The trigonometric area formula is expressed as: Area = 1/2 × ab × sin(C).
Find the area of one of the triangles:
a = 17 in.
b = 17 in.
C = 74°
Area = 1/2 × (17)(17) × sin(74) ≈ 139 sq. in.
Area of the three triangles = 3(139) = 417 square inches.
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