Answer key for a 2nd-grade math worksheet identifying faces on 3D shapes.

The task involves identifying whether specific 3D shapes have certain types of faces (circle, square, triangle, rectangle). Below is a detailed explanation of the solution for each shape:

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1. Cube

- Shape: A cube has 6 faces, and all of them are squares.
- Questions:
- Does it have a circle as a face? No (N)
- Does it have a square as a face? Yes (Y)

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2. Triangular Pyramid (Tetrahedron)

- Shape: A triangular pyramid has 4 faces, and all of them are triangles.
- Questions:
- Does it have a triangle as a face? Yes (Y)
- Does it have a square as a face? No (N)

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3. Cylinder

- Shape: A cylinder has 3 faces: 2 circular faces at the top and bottom, and 1 curved surface (which is not considered a flat face).
- Questions:
- Does it have a triangle as a face? No (N)
- Does it have a circle as a face? Yes (Y)

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4. Rectangular Prism

- Shape: A rectangular prism has 6 faces, and all of them are rectangles. Some of these rectangles can be squares if the prism is a cube.
- Questions:
- Does it have a square as a face? Yes (Y) (If any of the faces are squares)
- Does it have a triangle as a face? No (N)

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5. Square Pyramid

- Shape: A square pyramid has 5 faces: 1 square base and 4 triangular faces.
- Questions:
- Does it have a square as a face? Yes (Y)
- Does it have a triangle as a face? Yes (Y)

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6. Triangular Prism

- Shape: A triangular prism has 5 faces: 2 triangular bases and 3 rectangular lateral faces.
- Questions:
- Does it have a rectangle as a face? Yes (Y)
- Does it have a circle as a face? No (N)

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7. Cone

- Shape: A cone has 2 faces: 1 circular base and 1 curved surface (which is not considered a flat face).
- Questions:
- Does it have a triangle as a face? No (N)
- Does it have a circle as a face? Yes (Y)

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Final Answers

| Shape Image | Question 1 | Answer 1 | Question 2 | Answer 2 |
|-------------|------------|----------|------------|----------|
| 1. Cube | Circle? | N | Square? | Y |
| 2. Tetrahedron | Triangle? | Y | Square? | N |
| 3. Cylinder | Triangle? | N | Circle? | Y |
| 4. Rectangular Prism | Square? | Y | Triangle? | N |
| 5. Square Pyramid | Square? | Y | Triangle? | Y |
| 6. Triangular Prism | Rectangle? | Y | Circle? | N |
| 7. Cone | Triangle? | N | Circle? | Y |

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Explanation of the Solution

Each shape was analyzed based on its geometric properties:
- Cube: All faces are squares.
- Triangular Pyramid: All faces are triangles.
- Cylinder: Has circular faces but no triangular or square faces.
- Rectangular Prism: Can have square or rectangular faces.
- Square Pyramid: Has a square base and triangular lateral faces.
- Triangular Prism: Has triangular bases and rectangular lateral faces.
- Cone: Has a circular base but no triangular faces.

This approach ensures accurate identification of the faces for each 3D shape.

Final Answer:
\boxed{
\begin{array}{|c|c|c|c|c|}
\hline
\text{Shape Image} & \text{Question 1} & \text{Answer 1} & \text{Question 2} & \text{Answer 2} \\
\hline
1. \text{Cube} & \text{Circle?} & \text{N} & \text{Square?} & \text{Y} \\
\hline
2. \text{Tetrahedron} & \text{Triangle?} & \text{Y} & \text{Square?} & \text{N} \\
\hline
3. \text{Cylinder} & \text{Triangle?} & \text{N} & \text{Circle?} & \text{Y} \\
\hline
4. \text{Rectangular Prism} & \text{Square?} & \text{Y} & \text{Triangle?} & \text{N} \\
\hline
5. \text{Square Pyramid} & \text{Square?} & \text{Y} & \text{Triangle?} & \text{Y} \\
\hline
6. \text{Triangular Prism} & \text{Rectangle?} & \text{Y} & \text{Circle?} & \text{N} \\
\hline
7. \text{Cone} & \text{Triangle?} & \text{N} & \text{Circle?} & \text{Y} \\
\hline
\end{array}
}