The percent area A of {HEAD ~ the plane} in {TAIL ~ the slide surface} is set in a range of A≧50% 
in
The percent area A of { HEAD ~ the plane } in { TAIL ~ the slide surface } is set in a range of A≧50 %
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH