Question

Two lines with direction ratios \[(a_1,b_1,c_1)\] and \[(a_2,b_2,c_2)\] are perpendicular when:

Options

• \[a_1a_2+b_1b_2+c_1c_2=0\]

• \[\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}\]

• \[a_1^2+b_1^2+c_1^2=0\]

• \[a_2^2+b_2^2+c_2^2=0\]

Answer 1

A zero dot product means perpendicular lines. For direction ratios, the dot product is \[a_1a_2+b_1b_2+c_1c_2\].