Final answer:
To find the height of the plane, we can use trigonometry. The angle of elevation is 9 degrees, and the ground distance to the plane is 21,000 meters. Using the tangent function, we find that the height of the plane is approximately 3,140 meters.
Step-by-step explanation:
To find the height of the plane, we can use trigonometry. The angle of elevation from the ground to the plane is 9 degrees. We can use the tangent function to find the height of the plane. Tangent is equal to opposite over adjacent, where the opposite side is the height of the plane and the adjacent side is the ground distance to the plane. Using the formula tan(angle) = height/ground distance, we can substitute the values given in the question: tan(9) = height/21000. Solving for height, we get height = tan(9) * 21000. Plugging this into a calculator, we find that the height of the plane is approximately 3,140 meters.