[" Show that the triangle of maximum area that can be "A(2,1,2)" and "B(4,-2,1)" and "],[" equilateral triangle."],[" Find the equation of a plane passing through the points "A(2,1,2)" and "B" oint,where the "],[" Find the equation of a plane passing through the coordinates of the point,where the "],[" perpendicular to plane "vec r*(hat i-2hat k)=5" .Also,find the coordinates the plane thus obtained."],[" line passing through the points "(3,4,1)" and "(5,1,6)" crosses the plane thus obtained."]