Abstract:  This paper obtain that the radius of starlikencss for class S(a,n)in[l]is,tespxtively.... where  ta  is  uniquc   solution  of  cquation√m=n  with   a  in(0,1),and  a=[1+(1-2a)_,(1—²),  =[1-(1-2a)r]/(1+r).Futhermore,we   considcr   an   extension   of   class  ... where a=[1+(1-2a),2]/(5—m2)(0≤r<1),a∈(0,1)is somc fixcd numbcr.This rcsult is alsu the cxicnsion ofwel-known results [T,Th3]and [8.Th3j.

Key words: pick thcorcm, starlikc furectiun, radius of starlikencss