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en/13.1.16.md
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| + | ### Statement | ||
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| + | $13.1.16.$ [Insert the problem statement] | ||
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| + | ### Solution | ||
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| + | Conversely, we may ask where a light source should be placed in order that its image is formed $40$ cm behind the mirror. Using half the radius of curvature of the mirror as its focal length, we have | ||
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| + | \[u=\frac{vf}{v-f}=\frac{-40\cdot40}{-40-40}=20.\] | ||
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| + | Therefore, the object should be placed $20$ cm from the focal point toward the mirror. | ||
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| + | #### Answer | ||
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| + | [Insert a concise answer or boxed result] | ||
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| ### Statement | |||
| $13.1.16.$ [Insert the problem statement] | |||
| ### Solution | |||
|  | |||
| Conversely, we may ask where a light source should be placed in order that its image is formed $40$ cm behind the mirror. Using half the radius of curvature of the mirror as its focal length, we have | |||
| \[u=\frac{vf}{v-f}=\frac{-40\cdot40}{-40-40}=20.\] | |||
| Therefore, the object should be placed $20$ cm from the focal point toward the mirror. | |||
| #### Answer | |||
| [Insert a concise answer or boxed result] | |||