AP EAMCET Engineering 18 Sep 2020 Shift 1 Paper

Which of the following is false?
1) If (a,b,c) are direction ratios of aline,then a2+b2+c2≠1
2) The direction cosines of a line can be its direction ratios but not vice-versa.
3) If (l,m,n) is one set of direction cosines, then (−l,−m,−n) is also a valid set.
4) If (l1,m1,n1) and (l2,m2,n2) are direction cosines of perpendicular lines, then l1l2+m1m2+n1n2=1