How to Identify Prisms & Pyramids
- 1). Examine the cross section of the figure. The cross section refers to how the figure appears when you cut it along its length. For a prism, the cross section is the same whether you cut it at the front, the middle or the back. For example, a square prism has the cross section of a square. A triangular pyramid has the same shape cross section, but different size, depending on the orientation when you make the slice.
- 2). Look for an apex at the top of the figure. You can identify a pyramid based on whether or not it has an apex, or a point at which all of the sides converge. A prism does not have an apex at the top.
- 3). Examine the faces of the figure. In a prism, the two bases are parallel to one another, whereas all the faces of a pyramid intersect. Also, the shape of the top of a triangular prism extends downward to the base, whereas the apex at the top of a pyramid is a single point.
- 4). Know the formula of the volume for the prism and the pyramid. When identifying a prism and a pyramid, you may be given the formula for the volume. Depending on the formula, you will know which type of figure you are analyzing. The formula for the volume of the prism is the area of the end of the prism, multiplied by the length of the prism. The formula of the volume of a pyramid is one-third of the area of the base multiplied by the height.
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