From her eye, which stands 1.68 meters above the ground, Hannah measures the angle of elevation to the top of a prominent skyscraper to be 31degrees


. If she is standing at a horizontal distance of 194 meters from the base of the skyscraper, what is the height of the skyscraper? Round your answer to the nearest hundredth of a meter if necessary.

1 answer

To determine the height of the skyscraper, we can use the information provided and apply some basic trigonometry.

  1. Identify the given information:

    • Height from Hannah's eye level to the ground: \( h_{Hannah} = 1.68 \) meters
    • Angle of elevation to the top of the skyscraper: \( \theta = 31^\circ \)
    • Horizontal distance from Hannah to the base of the skyscraper: \( d = 194 \) meters
  2. Determine the height of the skyscraper above Hannah's eye level:

    • The relationship between the height of the skyscraper above her eye level and the angle of elevation and distance can be established using the tangent function: \[ \tan(\theta) = \frac{h_{skyscraper} - h_{Hannah}}{d} \] Rearranging this equation gives: \[ h_{skyscraper} - h_{Hannah} = d \cdot \tan(\theta) \] Therefore: \[ h_{skyscraper} = h_{Hannah} + d \cdot \tan(\theta) \]
  3. Calculate the height of the skyscraper: \[ h_{skyscraper} = 1.68 + 194 \cdot \tan(31^\circ) \]

  4. Calculate \(\tan(31^\circ)\): Using a calculator: \[ \tan(31^\circ) \approx 0.6009 \]

  5. Substitute this value into the equation: \[ h_{skyscraper} = 1.68 + 194 \cdot 0.6009 \] \[ h_{skyscraper} = 1.68 + 116.5196 \] \[ h_{skyscraper} \approx 118.1996 \text{ meters} \]

  6. Round the final height to the nearest hundredth: \[ h_{skyscraper} \approx 118.20 \text{ meters} \]

Therefore, the height of the skyscraper is approximately 118.20 meters.