The Pythagorean Theorem in Three Dimensions Quick Check

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Question
Melissa has a gerbil that lives in a cage in the shape of a rectangular prism. She wants to put a ramp in the cage to give her gerbil exercise. The cage has a length of 70 cm, a width of 35 cm, and a height of 50 cm. How long does the ramp need to be to fit diagonally in the cage? Round the answer to the nearest tenth.(1 point)
Responses

116.3 cm
116.3 cm

92.9 cm
92.9 cm

78.6 cm
78.6 cm

60.2 cm
60.2 cm
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1 answer

To find the length of the ramp that fits diagonally in a rectangular prism-shaped cage, we can use the three-dimensional version of the Pythagorean Theorem. For a rectangular prism (box), the formula for the diagonal \( d \) is:

\[ d = \sqrt{l^2 + w^2 + h^2} \]

where \( l \) is the length, \( w \) is the width, and \( h \) is the height of the prism.

In this case, the dimensions of Melissa's gerbil cage are given as:

  • Length \( l = 70 \) cm
  • Width \( w = 35 \) cm
  • Height \( h = 50 \) cm

Substituting these values into the formula, we calculate:

\[ d = \sqrt{70^2 + 35^2 + 50^2} \]

Calculating each component:

\[ 70^2 = 4900 \quad (1) \] \[ 35^2 = 1225 \quad (2) \] \[ 50^2 = 2500 \quad (3) \]

Now add these results together:

\[ 4900 + 1225 + 2500 = 8625 \]

Now take the square root of the total:

\[ d = \sqrt{8625} \approx 92.9 \text{ cm} \]

Rounding to the nearest tenth:

\[ d \approx 92.9 \text{ cm} \]

Thus, the correct response is:

92.9 cm