Congruency & Similarity
Success Criteria
Success Criteria
At the end of this chapter, students are able to:
At the end of this chapter, students are able to:
- Identify congruent and similar triangles.
- State the scale factor of enlargement and reduction for similar figures.
- Apply the ratio of corresponding sides for similar triangles.
- Apply the ratio of base for triangles of common heights.
- Apply the relationship between the ratio of areas and heights for similar plane figures.
- Apply the relationship between the ratio of volumes and heights for similar solids.
- Solve problems involving the ratio and areas and volumes of similar figures/solids (AO2).
Recap
Recap
In Sec 2, we learnt the definition of congruency & similarity.
In Sec 2, we learnt the definition of congruency & similarity.
Same shape implies that all 3 pairs of corresponding angles in both triangles are equal.
Same shape implies that all 3 pairs of corresponding angles in both triangles are equal.
Same size implies that the lengths of all 3 pairs of corresponding sides in both triangles are equal.
Same size implies that the lengths of all 3 pairs of corresponding sides in both triangles are equal.
Explore!
Explore!
Move the RED point to translate the triangle and use the sliders to rotate and enlarge / reduce the triangle.
Move the RED point to translate the triangle and use the sliders to rotate and enlarge / reduce the triangle.
Check on the reflection box to reflect about a vertical line at A. Use this applet to explore the properties of shapes of triangles under these transformations.
Check on the reflection box to reflect about a vertical line at A. Use this applet to explore the properties of shapes of triangles under these transformations.
Do they remain congruent / similar after translation, rotation, reflection and enlargement / reduction.
Do they remain congruent / similar after translation, rotation, reflection and enlargement / reduction.