★ Must-know
Further detail
Picture a unit circle marked from 0 around one complete turn to 2π.
📌 A radian measures an arc length on the unit circle, whereas a degree measures an angle relative to a full turn of 360 degrees.
1. What defines the unit circle?
2. What is the arc length of a half-turn on the unit circle?
3. Which statement correctly distinguishes radians from degrees?
What is the radius of the unit circle centered at the origin?
The radius is 1.
What is the positive direction on the trigonometric circle?
Counterclockwise is the positive direction.
What does a radian measure on the unit circle?
An arc length on the unit circle.
What is the conversion relation between radians and degrees?
.
Unit circle radius
Radius is 1, circumference is 2π.
Radian-degree relation
π radians = 180°.
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