A line which divides a shape in two is called a bisector.
This would be known as the Equator
When a ray divides an angle(Which is formed by 2 straight lines) in half that is equally on both the sides, it is termed as Angle Bisector.
That is the correct spelling of "bisect" (to divide equally in half, as in geometry).
Symmetry
to cut something in half equally
Half a circle is called a "semicircle" in geometry.
The sagittal plane divides the mouth into a right and left half.
A bisector divides an angle in half (usually in the form of a line passing through the centre of the angle).
The line that divides the Earth in half horizontally is known as the Equator. It is located at 0 degrees latitude and divides the Earth into the Northern Hemisphere and the Southern Hemisphere.
the equator
It is 180 degrees
The equator divides the earth into the north and south hemispheres.