Radian
See how to write and use the angle in radian measure.
5 examples and their solutions.
Radian
Formula
(rad) = (°)⋅π180
Radian is a way to write the measure of an angle.180° = π
Unit: rad (can be omitted)
Example
30° → rad?
Solution θ = 30⋅π180
= π6
= π6
Close
Example
π4 → °?
Solution θ⋅π180 = π4
θ180 = 14
θ = 1804
= 45°
θ180 = 14
θ = 1804
= 45°
Close
Mostly Used Angles in Radian
Formula
| ° | rad |
|---|---|
| 0° | 0 |
| 30° | π6 |
| 45° | π4 |
| 60° | π3 |
| 90° | π2 |
| 180° | π |
| 270° | 3π2 |
| 360° | 2π |
Length of an Arc (Radian)
Formula
l = rθ
Example
Length of AB = ?
Solution l = 6⋅2π3
= 3⋅2π
= 6π
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Area of the Sector of a Circle (Radian)
Formula 1
A = 12r2θ
Example
Area?
Solution A = 12⋅62⋅2π3
= 6π⋅2
= 12π
Close
Formula 2
A = 12rl
Example
Area?
Solution A = 12⋅4⋅3π
= 2⋅3π
= 6π
Close