meaning of half-plane in geometry?

Answer 1

http://en.wikipedia.org/wiki/Upper_half-plane
maybe this help.

Answer 2

In geometry, a half-space is any of the two parts into which a plane divides the three-dimensional space. More generally, a half-space is any of the two parts into which a hyperplane divides an affine space.

One can have open and closed half-spaces. An open half-space is any of the two open sets produced by the subtraction of a hyperplane from the affine space. A closed half-space is the union of an open half-space and the hyperplane that defines it.

If the space is two-dimensional, then a half-space is called a half-plane (open or closed). A half-space in a one-dimensional space is called a ray.

A half-space may be specified by a linear inequality, derived from the linear equation that specifies the defining hyperplane.

Answer 3

if you have microsoft works or word this is your answer
type half-plane on a blank document
then highlight it
now right click
scroll down to dictionary look up
the rest is common sense