SL 3.4—Radian measure
- Syllabus
- First assessment 2021
- Objective
- —
- Level
- SL
Use radians for arc length and sector area
Use radians for arc length and sector area.
Radians link angle to arc length: s=rθ and sector area=1/2r²θ when θ is in radians.
Worked example
For r=6 and θ=π/3, arc length is 2π and sector area is 6π.
Convert degrees before using the radian formulas.
Using degrees directly in s=rθ gives the wrong scale.