One radian is defined as the angle subtended at the centre of a circle by an arc whose length is
Correct answer: A. equal to the radius
- A. equal to the radius
- B. equal to the diameter
- C. equal to the circumference
- D. one metre
Explanation
Since the arc length equals the radius times the angle in radians, an arc of one radius length subtends exactly one radian, about 57.3 degrees. A full circle is therefore 2 pi radians, because the circumference is 2 pi times the radius. Defining the angle this way is what makes the arc length formula and the link between linear and angular quantities so simple.
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About Angular Displacement
Angular displacement measures the change in a body’s angular position and is expressed in radians or degrees, with anticlockwise and clockwise directions assigned signs. It connects to arc length, angular velocity and angular acceleration, and must be distinguished from ordinary linear displacement in rotational motion.
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