Answer:
17.5 feet
Explanation:
This is a right angled triangle. When we deal with or want to solve a question involving angle of depression, we use the Trigonometric function of tangent
Angle of Depression = θ = 31°
tan θ = Opposite side / Adjacent side
Opposite side = Height of the post = 10.5 feet
Adjacent side = Length of the driveway = Unknown
Hence,
tan 31° = 10.5 feet/Adjacent side
Cross Multiply
= tan 31° × Adjacent side = 10.5feet
Adjacent side = 10.5 feet/ tan 31°
= 17.474934565 feet
≈ 17.5 feet
The length of the driveway is approximately 17.5 feet