According to FIFA.
Allowable field dimensions:
Length: 90 m (100 yds) to 120 m (130 yds)
Width: 45 m (50 yds) to 90 m (100 yds)
For international matches:
Length: 100 m (110 yds) to 110 m (120 yds)
Width: 64 m (70 yds) to 75 m (80 yds)
30 feet
a gentle slope
They go up and down latitude lines go sideways
100 yards from tryline to tryline.
The land is relatively flat.
They can be any distance apart
Contour lines that are far apart indicate a gentle slope. Because contour lines connect points with the same elevation, wide spacing indicates that the elevation is not changing drastically.
they have to be close together if they are far apart it means it is a flat area
The side is determined by how far apart the ends are.
They show a narrow area
It depends how far apart they are. It could be an infinite number.
If the "contour interval" ... the elevation difference between lines ... is the same everywhere on the map, then the lines will be closer rogether on steep ground, and farther apart on flatter ground.