The coordinate plane is formed by the intersection of two perpendicular number lines called axes. The point of intersection, called the origin, is at 0 on each number line. The horizontal number line is called the x-axis, and the vertical number line is called the y-axis.

Points on the coordinate plane are described using ordered pairs Points on the coordinate plane are described using ordered pairs. An ordered pair consists of an x-coordinate and a y-coordinate and is written (x, y). Points are often named by a capital letter. The x-coordinate tells how many units to move left or right from the origin. The y-coordinate tells how many units to move up or down. Reading Math

Example 1: Graphing Points in the Coordinate Plane Graph each point. A. T(–4, 4) Start at the origin. T(–4, 4) • Move 4 units left and 4 units up. B. U(0, –5) Start at the origin. Move 5 units down. C. V (–2, –3) • V(–2, −3) Start at the origin. • U(0, –5) Move 2 units left and 3 units down.

Midpoint and Distance in the Coordinate Plane You can use formulas to find the midpoint and the length of any segment in the coordinate plane. Number Line Coordinate Plane

Finding the Midpoint Segment AB has endpoints at -4 and 9. What is the coordinate of its midpoint?

Finding the Midpoint Segment EF has endpoints E (7 , 5) and F (2 , -4). What are the coordinates of its midpoint M?

Finding an Endpoint The midpoint of segment CD is M(-2 , 1). One endpoint is C (-5 , 7). What are the coordinates if the other endpoint D?

Distance Formula The distance between two points A(x1 , y1) and B(x1 , y1) is

Finding Distance What is the distance between U(-7 , 5) and V(4 , -3)? Round to the nearest tenth?

Practice Page 56 1-9, 18-23