Why is it reasonable to use the same units to describe circles and angles?

Using the same units to describe circles and angles is reasonable because both concepts are inherently related through the circle's geometry. The circumference of a circle can be measured in linear units (like meters), while angles can be expressed in radians, which are defined based on the radius of the circle. One radian corresponds to an angle where the arc length is equal to the radius, creating a direct relationship between linear distance and angular measurement. Thus, utilizing the same units simplifies calculations and enhances understanding of circular motion and geometry.