The lines whose direction cosine are given by the relation a^2 l+b^2 m+c^2n=0 and mn+nl+lm=0 are parallel if1.(a^2-b^2+c^2)^2=4a^2c^22.(a^2+b^2+c^2)^2=4a^2c^23.(a^2-b^2+c^2)^2=a^2c^24.None of these
The lines whose direction cosine are given by the relation a^2 l+b^2 m+c^2n=0 and mn+nl+lm=0 are parallel if
1.(a^2-b^2+c^2)^2=4a^2c^2
2.(a^2+b^2+c^2)^2=4a^2c^2
3.(a^2-b^2+c^2)^2=a^2c^2
4.None of these