"Using Coordinates to Express Translation" Plane Cartesian Coordinate System PPT Courseware

"Using Coordinates to Express Translation" Plane Cartesian Coordinate System PPT Courseware

(1) The symmetry point of point (a, b) about the X-axis is (a, -b)

(2) The symmetry point of point (a, b) about the Y axis is (- a, b)

(3) The symmetry point of point (a, b) about the origin is (-a, -b)

Among the following statements about points A and B,

(1) If point A and point B are symmetrical about the y-axis, then their ordinates are the same;

(2) If the ordinates of point A and point B are the same, then they are symmetrical about the y-axis;

(3) If the abscissas of point A and point B are the same, they are symmetrical about the x-axis;

(4) If point A and point B are symmetrical about the x-axis, then their abscissas are the same,

The correct number is ()

A. 1 piece B. 2 pieces C. 3 pieces D. 4 pieces

Experience review

1. What is translation?

Moving a graphic as a whole a certain distance in a certain direction is called translation.

2. What is the relationship between the new shape obtained after translation and the original shape?

After translation, the position of the graphic changes, but the shape and size remain unchanged.

let me give it a try

Trace point A (-2, -3) in coordinates and translate as follows:

1. (1) Translate point A 5 units to the right to obtain point A1. Then the coordinates of point A1 are ________;

(2) Translate point A 3 units to the left to obtain point A2, then the coordinates of point A2 are ________;

(3) Translate point A to the right by a (a>o) unit length to obtain point An, then the coordinates of point An are ________;

(4) Translate point A to the left by a (a>o) unit length to obtain point An´, then the coordinates of point An´ are ________;

Summary rule 1: The relationship between graphics translation and point coordinate changes

(1) Left and right translation:

Point (x, y) on the original graphic is translated a unit to the right (x+a, y)

Point (x, y) on the original graphic is translated a unit (x-a, y) to the left

(2) Up and down translation:

Point (x, y) on the original graphic is translated upward by b units (x, y+b)

Point (x, y) on the original graphic is translated downward b units (x, y-b)

Inquiry activities

1. Translate △ABC vertex coordinates A(4,3), B(3,1), C(1,2) to the left by 6 unit lengths, draw the corresponding figure, and write the coordinates of each point. After translation What is the relationship between the shape, size and coordinates of each point of the original shape?

2. Translate △ABC vertex coordinates A(4,3), B(3,1), C(1,2) downward by 5 unit lengths, draw the corresponding figure, and write the coordinates of each point. After translation What is the relationship between the shape, size and coordinates of each point of the original shape?

Summary rule 2:

The relationship between the coordinate changes of points on the graph and the translation of the graph

(1) The abscissa changes and the ordinate remains unchanged:

Point (x, y), (x+a, y) on the original graph is translated a unit to the right.

Point (x, y) on the original graph, (x-a, y) translates a unit to the left

(2) The abscissa remains unchanged and the ordinate changes:

The point (x, y) on the original graph, (x, y+b) is translated upward b units

The point (x, y) on the original graph, (x, y-b) is translated downward b units

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"Using Coordinates to Express Translation" Plane Cartesian Coordinate System PPT Courseware 2:

"Using Coordinates to Express Translation" Plane Cartesian Coordinate System PPT Courseware 2 Review 1: Translation of a point (1) Left and right translation: Point (xy), translate a unit to the right (x+ay) Point (xy), translate a unit to the left units (x-ay) (2) Translate up and down: point (xy), translate up b units (xy..