Geometry
Arc length
The curved edge of the sector, which is the radius times the angle in radians.
The Formula
arc length = r x theta
The curved edge of the sector, which is the radius times the angle in radians.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| s | Arc length | any length unit | The curved edge of the sector. |
| r | Radius | any length unit | Distance from the centre to the arc. |
| theta | Angle in radians | radians | The central angle in radians. |
What Each Symbol Means
sany length unit
Arc length
The curved edge of the sector.
rany length unit
Radius
Distance from the centre to the arc.
thetaradians
Angle in radians
The central angle in radians.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate the area of a sector page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate The Area Of A Sector, filed under Math. Every number the guide produces comes from substituting into this one line.