The straight lines whose direction cosines are given by `al + bm + cn = 0`,` fmn + gnl +hlm=0`are perpendicular if

The straight lines whose direciton cosines are given by al + bm + cn = 0 , fmn + gnl + hlm = 0 if ............

Prove that the lines, whose direction cosines are given by al+bm+cn=0, fmn+gnl+hlm=0 are: perpendicular if f/a+g/b+h/c=0

Prove that the straight lines whose direction cosines are given by the relations al+bm+cn=0 and fmn+gnl+hlm=0 are Perpendicular to each other if (f)/(a)+(g)/(b)+(h)/(c)=0 , and parallel if a^(2)f^(2)+b^(2)g^(2)+c^(2)h^(2)-2bcgh-2cahf-2abfg=0 .

A straight line with direction cosines (0,1,0) is

Prove that the straight lines whose direction cosines are given by the equations al+bm+cn=0 and fmn+gnl+hlm=0 are parallel if a^(2)f^(2)+b^(2)g^(2)+c^(2)h^(2)-2(abfg+bcgh+cahf)=0

Show that the pair of staright lines whose direction cosines are given by al+bm+cn=0 and pl^(2)+qm^(2)+rn^(2)=0 are perpendicular to each other if a^(2)(q+r)+b^(2)(r+p)+c^(2)(p+q) =0

Show that the straight lines whose direction cosines are given by 2l + 2m - n = 0 and mn + nl + Im = 0 are at right angles.