what is radian?
how to use it? can you explain by using examples?
i know a formula related to radian : s= r(theta)
why it is better to use the formula to find length of arc rather than formula : (angle at the center)/360 times circumference ?
It is a better measure than degrees for many purposes because it is a natural unit (unlike the degree which is a 90-th part of a right angle). Which results in better properties for trig (and related) functions when expressed in radians compared to when expressed in degrees.