The angle  between  any  two  diagonals  of  a cube is

Line joining  A (5,2,-3)  to  B (6,1,4)  and  C(-3,-2,-1) to D (-1,-4,11)  are   

P,Q,R,S  are  the  points (-2,3,4)  (-4,4,6) , (4,3,5)  and (0,1,2).  Projection  of PQ  is

The distance  from  the origin to (2,2,3)  is

A  line makes   angles  of 45^o  and  60^o  with  the positive  axes of  x  and y  respectively.  What  angle  does it  make  with the positive  axis  of  z?

The angle  between  the lines  whose  direction cosines are √3/4, 1/4  , √3/2  and   √3/4, 1/4 ,   -√3/2  is  

For what value of x will the line through (5,1,-2)  and (-4,-5,13)  be  perpendicular  to  (-5,x,0)  and (9,-4,6) ?

If  given  that  the points  are A(-11,8,4), B (-1,-7,-1)   and  c(9,-2,4).  Then  the  lines  AB  and BC are

For what   value of   x  will  the line  through   (4,1,2)  and (5,x,O)  be  parallel  to the line through  (2,1,1)  and (3,3,-1).