Zusammenfassung der Ressource
Similarity and congruency
- Similarity
- Similar figures have the same shape but can be different sizes
- It can either be an enlargement or reduction
- Two polygons are similar if:
- Their corresponding angles are equal (matching angles)
- Their corresponding sides are in the same proportion
- The symbol for similar is |||
- If two triangles have equal corresponding angles, their corresponding sides are in proportion
- If two triangles have corresponding sides in proportion, corresponding angles are equal
- You have to put the triangle in the order that it corresponds with the other triangle to find out whether it is similar
- Congruency
- To prove congruency compare, sides and anlges.
- Congruent means identical and equal in all respects (2 triangles must be compared)
- There are 4 cases of congruency
- 1. If three sides of a triangle are respectively equal to the three sides of the other triangle then the two triangles are congruent (SSS)
- 2. If two sides and included angle of a triangle is respectively equal to the two sides and the included angle of another triangle ten they are congruent (SAS)
- 3.If two angles and one side of one triangle are respectively equal to two angles and the corresponding side of another triangle, they are congruent (AAS or ASA)
- 4.If the hypotenuse and one side of a right-angled triangle are respectively equal to the hypotenuse and one side of another right-angled triangle, they are congruent (RHS)
- RHS - Right-angle, hypotenuse & side
- The symbol for congruency ->