To find the length of \( d \), which represents the space diagonal of the rectangular prism, we can use the formula for the space diagonal of a rectangular prism, given by:
\[ d = \sqrt{l^2 + w^2 + h^2} \]
Substituting the values for \( l \), \( w \), and \( h \):
- \( l = 30 \) in
- \( w = 20 \) in
- \( h = 18 \) in
We calculate \( d \) as follows:
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Calculate \( l^2 \): \[ l^2 = 30^2 = 900 \]
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Calculate \( w^2 \): \[ w^2 = 20^2 = 400 \]
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Calculate \( h^2 \): \[ h^2 = 18^2 = 324 \]
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Now, add these three values together: \[ l^2 + w^2 + h^2 = 900 + 400 + 324 = 1624 \]
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Finally, take the square root to find \( d \): \[ d = \sqrt{1624} \]
Calculating the square root gives: \[ d \approx 40.31 \]
Rounding to the nearest tenth: \[ d \approx 40.3 , \text{in.} \]
Thus, the length of \( d \) is approximately 40.3 in.