The triangle pyramid is made up of 4 triangles.
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Formula:
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Area of triangle = 1/2 x base x height
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Area of the bottom triangle:
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Area = 1/2 x 9 x 7.8
Area = 35.1 yd²
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Area of the 3 side triangles:
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Area = 3 [ 1/2 x 9 x 10 ]
Area = 135 yd²
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Total Area:
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Total Area = 135 + 35.1
Total Area = 170.1 yd²
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Answer: Surface Area = 170.1 yd².
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