- To transform a figure (shape) means changing the size, location, and direction it faces.
- The figure before the transformation is called the pre-image.
- The figure after the transformation is called the image.
- If the pre-image is labeled as A, then the image would be labeled as A' (pronounced as A prime).
- There are four different types of transformation.
- Two figures are congruent if they are of the same shape and size.
- The image after rotation is congruent with the pre-image.
- The symbol for congruency is ≅
- A type of transformation that flips a figure across a line.
- It creates a mirror image (congruent figure). Congruent means the pre-image and the image have the same size and shape.
Question 1: What is the reflection of a point (2, -7) across the x-axis?
Solution: The reflection of a point (x, y) across the x-axis is the point (x, -y). So, the reflection of the point (2, -7) will be (2, 7).
Question 2: What is the reflection of a point (-3, 12) across the y-axis?
Solution: The reflection of a point (x, y) across the y-axis is the point (-x, y). So, the reflection of the point (-3, 12) will be (3, 12).
Question 3: Find the reflection of a point (-5, 1) across the line ?
Solution: The reflection of a point (x, y) across the line is the point (y, x). So, the reflection of the point (-5, 1) across will be (1, -5).
Question 4: Point is obtained after reflection of the point about the x-axis as shown in the graph. Find the coordinates of the point .
Solution: If point is reflected over the x-axis, the new point coordinate is . Point when reflected over the x-axis will produce .
- A reflection flips a figure over a line of reflection to create a mirror image.
- Each reflected point of the figure should have the same distance from the line of reflection on the opposite side.
- The reflected image and pre-image are congruent.
- In a coordinate plane, the image can be reflected around both axes.
- Differentiate between pre-image (A) and image (A').
- Differentiate between the x-axis and y-axis as the line of reflection.