S 3 2 1. Arc Length Formula if th is in degrees s 2 p r th360 Arc Length Formula if th is in radians s ϴ r. Thus in the unit circle the arc whose cosine is x is the same as the angle whose cosine is x because the length of the arc of the circle in radii is the same as the measurement of the angle in radians.
A r 2 th2 when th is measured in radians and.
Arc Length Formula s L ds L d s. This angle measure can be in radians or degrees and we can easily convert between each with the formula p radians 180 p r a d i a n s 180. S 2prth360 when th is measured in degrees and. The length of an arc is found by forming a ratio of the arc to the whole circle then multiplying it by the formula for circumference either 2pr 2 p r or pd p d like this.