NotesMath · P6Circles
Circles & Composite Figures Notes
Radius, diameter, circumference, area — and curved figures.
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Circle parts
Radius drives every circle formula.
1
Core Formulas
Use π = 22/7 or 3.14 as told.
- Circumference = 2πr = πd
- Area = πr²
- Semicircle area = ½πr²
- Quarter circle area = ¼πr²
2
Composite Figures
Split the figure into simple shapes. Add or subtract areas.
3
Perimeter vs Area
Perimeter uses curved LENGTH (πr or ½πd). Area uses πr².
Common Mistakes
- Using diameter as radius
- Adding straight edges twice when splitting figures
- Mixing π = 22/7 with a decimal answer
Teaching Team Tip
Draw the split lines on the composite figure before writing any working.
Worked Example
Try it, then check the steps
Question
A quarter circle of radius 14 cm. Find its area. (Use π = 22/7)
Steps
- 1Area = ¼ × 22/7 × 14 × 14
- 2= ¼ × 22/7 × 196
- 3= 154 cm²
What to do next
Learn Circles
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