Junior Cycle · Area, Volume and Measurement
⏱ Tested in 2 exam questions since 2023
Lesson 2 of 7
JCHL AVM 2: Circles and Sectors
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- Radius = centre to edge; Diameter = all the way across = two radii. The formulas use the radius, so halve a diameter first
- Circle (page 8): area A = πr², circumference l = 2πr. Your maths tables call the length round the outside l, not C
- Sector (page 9): the circle formulas times the fraction θ/360 — arc length l = 2πr(θ/360), area A = πr²(θ/360)
Formula used
l = 2π r, A = π r²
l = 2π r × θ/(360°), A = π r² × θ/(360°)
On page 8 of the log tables — read it off, don’t memorise.Most recent exam questions
- 2025 Q7(a)(i)
- 2025 Q7(a)(ii)
- 2023 Q12(b)(ii)
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