# Thread: radian

1. ## radian

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 ?

2. Originally Posted by reneelyn
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 ?
Radians measure angles. The measure is the length of the arc of a unit circle subtended by the angle at the centre of the circle.

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.

RonL

3. Originally Posted by reneelyn
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 ?
Just restating what capt. said.

Radians are a different way to measure degrees, instead of a right angle being $90^o$ in radians it's $\frac{\pi}{2}$

it's more useful to use radians in certain situations (it's like using kilometres instead of miles, it's easier to work with)