Here's why:

* Radians are a natural unit for angular measurement: They relate the arc length of a circle to its radius. One radian is the angle subtended by an arc whose length is equal to the radius of the circle.

* Radians simplify mathematical calculations: When working with angular velocity, acceleration, and other related concepts, using radians simplifies the equations and avoids unnecessary conversion factors.

While degrees are also used to measure angles, radians are preferred in physics and engineering because they are more convenient for calculations involving circular motion and other angular concepts.