दर्शाइए कि दिक्-कोसाइन `(12)/(13), (-3)/(13), (-4)/(13) , (4)/(13), ( 12)/(13), (3)/(13) , (3)/(13), (-4)/(13), (12)/(13) ` वाली तीन रेखाएँ परस्पर लंबवत है |

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

(9)/(13)+(-8)/(13)+(4)/(3)+(-5)/(8)

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 .

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.

(8)/(4)-(6)/(3)+(9)/(12)-:(15)/(13)

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

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

4/13 + 9/13 + 2/13 = ?/13

(2/13)^(4/3)div(2/13)^(5/3)

12(1)/(3)+10(5)/(6)-7(2)/(3)-1(4)/(7)=?( a) 11(13)/(14) (b) 13(11)/(14)(c)13(13)/(14) (d) 14(11)/(13) (e) None of these