9. From a point on the floor, the angle of elevation to the top of a doorway is \( 43^{\circ} \). The angle of elevation to the ceiling directly above the doorway is \( 56^{\circ} \). If the ceiling is 10 feet above the floor, how high is the doorway? How far in front of the doorway were the angles of elevation measured?
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The Deep Dive
To solve this problem, we can use some trigonometry! Let's denote the height of the doorway as \( h_d \) and the horizontal distance from the point on the floor to the base of the doorway as \( d \). 1. **Using the angle of elevation to the ceiling:** We have the angle of elevation to the ceiling \( 56^{\circ} \). \[ \tan(56^{\circ}) = \frac{\text{opposite}}{\text{adjacent}} = \frac{10}{d} \] Rearranging it gives us: \[ d = \frac{10}{\tan(56^{\circ})} \] 2. **Using the angle of elevation to the top of the doorway:** The angle of elevation to the top of the doorway is \( 43^{\circ} \). \[ \tan(43^{\circ}) = \frac{h_d}{d} \] Substitute \( d \) from our previous equation: \[ h_d = d \cdot \tan(43^{\circ}) = \frac{10 \cdot \tan(43^{\circ})}{\tan(56^{\circ})} \] Now, you can plug in the values of \( \tan(43^{\circ}) \) and \( \tan(56^{\circ}) \) from a calculator to find \( d \) and \( h_d \). Calculating these out gives: \[ d \approx \frac{10}{1.4826} \approx 6.73 \text{ feet} \] Then for \( h_d \): \[ h_d \approx \frac{10 \cdot 0.9325}{1.4826} \approx 6.29 \text{ feet} \] So, the height of the doorway is approximately **6.29 feet**, and the point from which the angles were measured is about **6.73 feet** in front of the doorway.