The straight lines whose direction cosines are given by al + bm + cn = 0, f m n + gnl + hlm = 0 are perpendicular i

### Question Asked by a Student from EXXAMM.com Team

Q 2166134075.     The straight lines whose direction cosines are given by

al + bm + cn = 0, f m n + gnl + hlm = 0 are perpendicular if
A

f/a + g/b + h/c =0

B

a^2/f + b^2/g + c^2/ h =0

C

a^2 (g+h) + b^2 (h+f) + c^2 (f+g) = 0

D

none of the above

#### HINT

(Provided By a Student and Checked/Corrected by EXXAMM.com Team)

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