Use the model for the base of a triangular prism and triangular pyramid. If the heights are both 9 cm, what is the volume of each shape?

(1 point)
Responses

prism: 36 cm3
; pyramid: 108 cm3
prism: 36 cm cubed ; pyramid: 108 cm cubed

prism: 108 cm3
; pyramid: 36 cm3
prism: 108 cm cubed ; pyramid: 36 cm cubed

prism: 72 cm3
; pyramid: 216 cm3
prism: 72 cm cubed ; pyramid: 216 cm cubed

prism: 216 cm3
; pyramid: 72 cm3

1 answer

To calculate the volumes of the triangular prism and triangular pyramid, we first need to know the area of the base triangle.

Let’s denote:

  • The area of the base triangle as \( A \) (in square centimeters).
  • The height of both the prism and pyramid as \( h = 9 \) cm.

Volume of the Triangular Prism

The volume \( V \) of a prism is given by: \[ V = A \times h \]

Volume of the Triangular Pyramid

The volume \( V \) of a pyramid is given by: \[ V = \frac{1}{3} A \times h \]

Let's Calculate Each Volume

  1. Triangular Prism: \[ V_{prism} = A \times h = A \times 9 \]

  2. Triangular Pyramid: \[ V_{pyramid} = \frac{1}{3} A \times h = \frac{1}{3} A \times 9 = 3 A \]

Finding the Relationship between Volumes

The volume of the prism is three times the volume of the pyramid (since \( V_{prism} = 3 \times V_{pyramid} \)): \[ V_{prism} = 3 V_{pyramid} \]

Answers Based on Choices

From the responses:

  1. If \( V_{prism} = 36 \) cm³, then \( V_{pyramid} = 12 \) cm³ (not listed).
  2. If \( V_{prism} = 108 \) cm³, then \( V_{pyramid} = 36 \) cm³ (not listed).
  3. If \( V_{prism} = 72 \) cm³, then \( V_{pyramid} = 24 \) cm³ (not listed).
  4. If \( V_{prism} = 216 \) cm³, then \( V_{pyramid} = 72 \) cm³ (not listed).

The correct answer would follow the relationship derived above. Therefore:

  • The options given do not directly reflect values for volumes that adhere to \( V_{prism} = 3 \times V_{pyramid} \).

If we assumed \( A = 12 \):

  • Prism: \( 12 \times 9 = 108 \) cm³
  • Pyramid: \( \frac{1}{3} \times 12 \times 9 = 36 \) cm³

Thus, the correct option based on our derivation should be: prism: 108 cm³; pyramid: 36 cm³.