Find the values of a so that the following lines `(x-1)/2 = ( y-2)/3 = (z-a)/4` and `(x-4)/5 = (y-1)/2 = z`

Find the values of a so that the following lines are skew. (x-1)/(2) = (y-2)/(3) = (z-a)/(4), (x-4)/(5) = (y-1)/(2) = z .

Show that the lines (x-1)/(2)=(y-2)/(y-1)=(z-3)/(4) and (x-4)/(5)=(y-1)/(2)=z intersect

Find the point of intersection of the lines (x-1)/(2)=(y-2)/(3)=(z-3)/(4) and (x-4)/(5)=(y-1)/(2)=z .

Find the angle between the following lines (x+1)/(1)=(y-4)/(1)=(z-5)/(2) and (x+3)/(3)=(y-2)/(5)=(z+5)/(4)

Find the angle between the following pair of lines: (x-2)/2=(y-1)/5=(z+3)/(-3) and (x+2)/(-1)=(y-4)/8=(z-5)/4

Find the angle between the following pairs of lines : (x-2)/2=(y-1)/5=(z+3)/-3 and (x+2)/-1=(y-4)/8=(z-5)/4