Key learning points

1. If two shapes are congruent, then they are similar.
2. A ratio table can be a helpful tool for checking the multipliers.
3. The multiplicative relationship between the sides of the object is preserved in its image.
4. It can be easier to determine (by eye) which shapes are NOT congruent or similar.

Keywords

• Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.

• Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.

• Object - The object is the starting figure, before a transformation has been applied.

• Image - The image is the resulting figure, after a transformation has been applied.

• Invariant - A property of a shape is invariant if that property has not changed after the shape is transformed.

Common misconception