Show that the three lines with direction cosines `(12)/(13),(-3)/(13),(-4)/(13),4/(13),(12)/(13),3/(13);3/(13),(-4)/(13),(12)/(13)` are mutually perpendicular.

Show that the three lines with direction cosines quad (12)/(13),(-3)/(13),(-4)/(13),(4)/(13),(12)/(13),(3)/(13);(3)/(13),(-4)/(13),(12)/(13) are mutually perpendicular.

Show that the three lines with direction cosines (12)/(13),(-3)/(13),(-4)/(13),(12)/(13),(3)/(13),(-4)/(13),(12)/(13) are mutually perpendicular.

Show that the lines with direction cosines ((12)/(13),(-3)/(13),(-4)/(13))and((4)/(13),(12)/(13),(3)/(13)) are perpendicular to each other.

Check if lines with direction-cosines : lt (12)/(13) , - (3)/(13) , - (4)/(13) gt , lt (4)/(13) , (12)/(13), (3)/(13) gt , lt (3)/(13) , (4)/(13) , (12)/(13) gt are mutually perpendicular .

(-4)/(13)+0=0+(-4)/(13)

Find: ((-8))/(13)+((-4))/(13)

((12)/(17)times(12)/(17)-(13)/(34)times(13)/(34))/((12)/(17)+(13)/(34))

Solve : 4/(13)+2/(13)+1/(13)

Solve : 4/(13)+2/(13)+1/(13)