An airplane is 50 km north and 70 km east of an airport. It is 7 km up in the air. What is the angle alon ground that the airplane is at, as a direction east of north?

a. 55.7°

c. 54.5°

b. 49.4°

d. 62.4°

To find the angle, we can use trigonometry to calculate the tangent of the angle.

Tangent = Opposite / Adjacent

In this case, the Opposite side is 70 km (east) and the Adjacent side is 50 km (north). Therefore, the tangent of the angle is:

Tangent = 70 km / 50 km = 1.4

To find the angle, we need to take the inverse tangent (arctan) of 1.4:

Angle = arctan(1.4) ≈ 54.5°

Therefore, the airplane is at an angle of approximately 54.5° east of north. The correct answer is option c. 54.5°.