Answer:
62.2° (or 1.1 rad)
Step-by-step explanation:
Let’s call the three points A Allen’s house, B Bob’s house, T the traffic light and α “angle of depression”.
Since we have a right triangle BTA, let’s first find out the angle ∡BTA based on its opposite side AB = 7 km and the hyponenuse TA = 15 km.
∡BTA = arcsin(AB/TA) ≈ arcsin(0.4667) ≈ 0.4855 rad or 27.82°
Now since the text says the connecting line TA “is vertical to the road”, α is the rest of the right angle when ∡BTA subtracted.
α ≈ 90° - 27.82° = 62.18°
or α ≈ 0.5 π rad - 0.4855 rad ≈ 1.09 rad
See above for properly rounded values.
