An observer (O) spots a plane flying at a 35° angle to his horizontal line of sight. If the plane is flying at an altitude of 17,000 feet, what is the distance (x) from the plane (P) to the observer (O)?

A right triangle is shown with angle O marked 35 degrees, hypotenuse marked x, and height marked 17,000 feet.

20,757 feet
24,251 feet
29,639 feet
31,262 feet

1 answer

To find the distance \( x \) from the plane (P) to the observer (O), we can use the relationship in a right triangle involving the angle of elevation and the altitude.

The altitude of the plane is the opposite side of the triangle, while \( x \) is the hypotenuse.

From trigonometry, we can use the sine function to find the hypotenuse:

\[ \sin(\theta) = \frac{\text{opposite}}{\text{hypotenuse}} \]

where \( \theta \) is the angle of elevation (35°) and the opposite side is the altitude (17,000 feet).

Rearranging the formula to solve for the hypotenuse \( x \):

\[ \sin(35°) = \frac{17,000}{x} \]

\[ x \cdot \sin(35°) = 17,000 \]

\[ x = \frac{17,000}{\sin(35°)} \]

Now we can calculate \( x \):

  1. Find \( \sin(35°) \): \[ \sin(35°) \approx 0.5736 \]

  2. Substitute into the equation: \[ x = \frac{17,000}{0.5736} \approx 29,635 \text{ feet} \]

Rounding this, we find:

\[ x \approx 29,639 \text{ feet} \]

Thus, the distance from the plane to the observer is approximately 29,639 feet.