Circles, arcs and sectors
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 7 practice questions, 1 real past-paper question with the answer explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Pizza slices
- Circumference and area
Read the transcript of the teaching part
Last time
Before we start: last time, in Circle theorems, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Pizza slices
A pizza has a crust all the way round, and a cheesy middle. The crust length is the circumference, and the cheese is the area. Cut out one slice: its curved edge is an arc, and the slice itself is a sector. They are just fractions of the whole pizza, and today you find each one.
Circumference and area
The circumference is the distance round. It is pi times the diameter, or two pi times the radius. The area is pi times the radius squared. Square the radius first, then multiply by pi. With radius seven: circumference is forty-three point nine eight. Area is a hundred and fifty-three point nine four.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Arcs and sectors.
The whole chapter: Units, Perimeter, Area, Circles and Sectors.
Chapter 23: Circles and areas
- Circles, arcs and sectors 5 min
- Perimeter and area of polygons 5 min
Also for O Level Maths 4024
Which topics come up most in O Level Maths 4024 past papers, counted from every paper since 2004.