1. Lesson B.1 The Cartesian Plane
Objective
Students will:
Plot points on the Cartesian plane and sketch scatter plots
Use the distance formula to determine the distance between two points
Use the Midpoint Formula to find the midpoint between two points
Find the equation of a circle
Translate points in the plane

2. The Cartesian Plane (pp. A25, A26)
Know the parts
x-axis, y-axis, origin, quadrants, coordinates
Be able to graph a point
Sketch a scatter plot
Independent variable on x-axis (time)

3. The Coordinate Plane Quadrant II Quadrant I Quadrant III Quadrant IV
y - axis
A point is named by an ordered pair written as
(x, y) → (3, 2)
(x, y) → (-2, -1)
Quadrant II
Quadrant I
Origin: (0, 0)
x - axis
Quadrant III
Quadrant IV

4. Distance Formula (pp. A27, A28)
Comes from the Pythagorean Theorem
An error just means you typed it in wrong

5. The Midpoint Formula (pp. A28-A29)
Think of it as averaging 2 coordinates
Your answer is always an ordered pair

6. Equation of a Circle (pp. A29-A30)
Center of the circle is at (h, k)
If the center is (-1, -5) then equation is (x + 1)2 + (y + 5)2…
r is the radius
The distance from the center to any point on the circle is the radius

7. Translating in the Plane (p. A31)
Adding values to an ordered pair will shift it in the plane
(x + 3, y – 2) will shift three right, two down

8. Reflections (p. A31)
What happens when you reflect about the y-axis, x-axis, or origin?
Reflections: opposite coordinates
(x, y) → (-x, y) reflect about y-axis
(x, y) → (x, -y) reflect about x-axis
(x, y) → (-x, -y) reflect about origin

9. Examples
Find the distance between and midpoint of points (-2, 3) and (4, -5)
A circle has a center at (3, 4). The point (8, 16) is on the circle. Write an equation for this circle in standard form.
Give the coordinates of the following vertices of a triangle after a reflection about the origin: (2, 3), (5, -1), (8, 6)