Answer: 33.4 cm²
A triangle pyramid has 4 faces.
To find the surface area, we add the area of all the 4 faces.
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Find the area of the base
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Area of the triangle = 1/2 x base x height
Area of the triangle = 1/2 x 4.5 x 3.9
Area of the triangle = 8.775 cm²
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Area of the 3 triangles at the side
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Area of 1 triangle = 1/2 x 3.5 x. 4.5
Area of 1 triangle = 7.875
Area of 3 triangles = 7.875 x 3
Area of 3 triangles = 23.635 cm²
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Surface Area
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23.635 + 8.775 = 32.4cm²
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Answer: 33.4 cm²
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