Transformation in Geometry

2. Transformation in Geometry Lesson 9

3. Aim: Identifying and describing transformation For this lesson we will: • Rotate a geometric figure. • Reflect a figure over a line of symmetry. • Translate a figure by sliding it to a different location. • Use dilation by enlarging or reducing the size of a figure without changing its form or shape.

4. Transformation A rule for moving every point in a plane figure to a new location.

5. Translation A transformation that moves each point in a figure the same distance in the same direction.

6. In a translation a figure slides up or down, or left or right. No change in shape or size. The location changes. • In graphing translation, all x and y coordinates of a translated figure change by adding or subtracting.

7. Reflection A transformation where a figure is flipped across a line such as the x-axis or the y-axis.

8. In a reflection, a mirror image of the figure is formed across a line called a line of symmetry. No change in size. The orientation of the shape changes. In graphing, a reflection across the x -axis changes the sign of the y coordinate. A reflection across the y-axis changes the sign of the x-coordinate.

9. Rotation A transformation where a figure turns about a fixed point without changing its size and shape.

10. In a rotation, figure turns around a fixed point, such as the origin. No change in shape, but the orientation and location change. • Rules for rotating a figure about the origin in graphing. • Rules for 90 degrees rotation- Switch the coordination of each point. Then change the sign of the y coordinate. Ex. A (2,1) to A’ ( 1,-2)

11. Dilation A transformation where a figure changes size.

12. Dilation • In dilation, a figure is enlarged or reduced proportionally. No change in shape, but unlike other transformation, the size changes. • In graphing, for dilation, all coordinates are divided or multiplied by the same number to find the coordinates of the image.