The train descends at twice the speed compared to its ascent, and it travels at 2/3 of the speed uphill relative to flat terrain.
If its speed downhill is measured at 120 miles per hour, its uphill speed would be 120 divided by 2, equaling 60 miles per hour, and its speed on flat ground would be 60 divided by (2/3), simplified to (60 times 3) divided by 2, resulting in 90 miles per hour.
Consequently, for the train to cover 45 miles on flat terrain, the time required is calculated as 45 divided by 90, which is equal to 0.5 hours, or 30 minutes.
Response:
D. The sidelines are parallel because they are perpendicular to a common line.
Justification:
According to the perpendicular transversal theorem, when a line is perpendicular to one of two parallel lines, it is also perpendicular to the other line. Furthermore, the converse of the theorem states that if two lines are perpendicular to the same line, they must be parallel. Therefore, the sidelines are indeed parallel and also perpendicular to this single line.
A 40-degree angle may be applicable for this question