Edexcel IGCSE Maths 復習筆記 4.17.1 Similarity - Lengths
Edexcel IGCSE Maths 復習筆記 4.17.1 Similarity - Lengths
What are similar shapes?
- Two shapes are?mathematically similar?if one is an enlargement of the other
- Equivalent?angles?in the two shapes will be equal
- Equivalent?lengths?in the two shapes will be in the same ratio and are linked by a?scale factor?(which you will normally have to find)
Working with similar shapes
- Identify?equivalent?known lengths
- Establish?direction?(getting bigger or smaller?)
- Find?scale factor?= Second Length ÷ First Length(Check that SF > 1 if getting bigger and SF < 1 if getting smaller)
- Use?scale factor?to find length
Exam Tip
If similar shapes overlap on the diagram (or are not clear) draw them separately!For example, in this diagram the triangles ABC and APQ are similar:So we would redraw them separately before we start:
Worked Example
轉載自savemyexam
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