90 degree bisector
It is an asymptote.
A bisector
When a line divides another in two equal parts, it is called a bisector. If the bisector happens to cross the other line at right angles, it is called a perpendicular bisector.
numerator and denominator
The equator is the parallel that divides the Earth into two equal parts, with one half in the Northern Hemisphere and the other half in the Southern Hemisphere.
The answer depends on how many equal parts there are.
Grads or Gradians!
Cook Straight
Exterior angle.
It is called a great circle. The equator is an example.
Square.
Twelfths.