Consider two circles, centered at the origin, of radii 1 and 2, respectively. In each circle, begin on thepositive x-axis and rotate...

An arc length represents a portion of the entire circumference of a circle with 360˚.

The circumference of a circle is defined by the formula: `C = 2pir`

A circle with a radius of 1 has a circumference of:

`C = 2pi*1 = 2pi`

Therefore the arc length would be:  

`210/360* 2pi = (7pi)/6` or  3.67 units

A circle with a radius of 2 has a circumference of:

`C=2pi*2 = 4pi`

Therefore the arc length would be:

`210/360* 4pi = (7pi)/3` or 7.33 units

The radian measures are given respectively as:

`(7pi)/6` and `(7pi)/3` as previously found when calculating units.

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