4.1 Radian Measure

 okay

now, i'm going to talk about radian measure which we should have known in secondary school if you took additional mathematics.

As a reminder:

θ = a / r 

where θ  should be in radian but not degree

a: length of arc subtended by the angle

r: radius

to convert a degree measure to a radian measure, we have to multiply the degree measure by π / 180° radians.




another stuff is angular velocity
if i am not mistaken, we didn't learn in secondary school


well,
angular velocity is the rate at which the central angle changes with respect to time


angular velocity = (degree/360° )(number of revolutions) / time in second