Key Word: xy-plane
Answer: A plane formed by a horizontal number line (the x-axis) and a vertical number line (the y-axis) that intersect at the zero point of each. This is also called the Cartesian coordinate system or coordinate plane.
Key Word: half plane
Answer: The graph of a linear inequality with two variables. If the inequality sign is < or >, the line is dashed to show that it is not included in the solution. If the inequality sign is ≤ or ≥, the line is solid to show that it is included in the solution.