To calculate the amount of red foil needed for the faces of the triangular prism-shaped candy bar, we first need to determine the dimensions of the prism based on the information given.
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Identifying the Shape and Dimensions:
- The prism has a triangular base.
- The width (the base of the triangle) is 20 cm.
- The height of the triangle is 6 cm.
- The length of the prism (the length along the triangular prism) is 10 cm.
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Calculating the Area of the Triangle (Base): The area of the triangular base can be calculated using the formula: \[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \] where the base is 20 cm and the height is 6 cm: \[ \text{Area} = \frac{1}{2} \times 20 , \text{cm} \times 6 , \text{cm} = \frac{1}{2} \times 120 , \text{cm}^2 = 60 , \text{cm}^2 \]
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Calculating the Area of the Faces: The prism has two triangular bases (top and bottom), which are covered in gold foil (not counted in the red foil requirement), and three rectangular side faces.
- Each triangular base area has been calculated as 60 cm².
- Therefore, the top and bottom areas together do not contribute to the red foil.
Now, let's calculate the area of the three rectangular faces that will be covered in red foil:
- Each side face of the prism has a height equal to the length of the prism (10 cm) and a width equal to the base of the triangle (20 cm).
The area of the first rectangular face is: \[ \text{Area}_{\text{rect1}} = \text{width} \times \text{length} = 20 , \text{cm} \times 10 , \text{cm} = 200 , \text{cm}^2 \]
The second and third faces are identical to the first, as they also have the dimensions of width and length.
Let's summarize:
- \(\text{Area of all three rectangular faces} = \text{Area}{\text{rect1}} + \text{Area}{\text{rect2}} + \text{Area}_{\text{rect3}} = 200 , \text{cm}^2 + 200 , \text{cm}^2 + 200 , \text{cm}^2 = 600 , \text{cm}^2\)
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Total Red Foil Needed: Thus, the total area of red foil needed for one candy bar is: \[ \text{Total Red Foil Area} = 600 , \text{cm}^2 \]
Therefore, 600 cm² of red foil are needed for one candy bar.