Transformation in Geometry Created by Ms. O. Strachan
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.
Transformation A rule for moving every point in a plane figure to a new location.
Translation A transformation that moves each point in a figure the same distance in the same direction.
In a translation a figure slides up or down, or left or right 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.
Reflection A transformation where a figure is flipped across a line such as the x-axis or the y-axis.
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.
Rotation A transformation where a figure turns about a fixed point without changing its size and shape.
In a rotation, figure turns around a fixed point, such as the origin 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)
Dilation A transformation where a figure changes size.
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.