Let  be Unit Vectors Such That . Which One Of The Following Is Correct?

A unit vector making an obtuse angle with x-axis and perpendicular to the plane containing the points  also makes an obtuse angle with

 is a unit vector such that 

 then a unit vector normal to the vectors  

A unit vector perpendicular to both 

If  are the position vectors of the vertices A, B, C of a triangleABC, then the area of triangle ABC is  

If , then the length of the perpendicular from A to the line BC is 

The perpendicular distance of the point  from the line joining 

If the diagonals of a parallelogram are represented by the vectors , then its area in square units is

If  are three vectors such that  then

Let  be a unit vector perpendicular to unit vectors  and if the angle between  is α, then  is