for cycloid the proof was given in terms of angle,later it was told that at radius =1 and speed=unity, angle may be replaces with time.thus r vector of cycloid was arrived at in terms of t.also using this r in terms of t, speed was calculated as  sqrt(2-2cost).my question is when  relation in terms of t was arrived at by using speed =unity,why it is coming as sqrt(2-2cost) ?####[['proof', 'Mathematical_Related_Concept', 'POS'], ['sqrt(2-2cost)', 'Mathematical_Related_Concept', 'NEG']]