Question

Which statement correctly describes direction ratios?

Options

• Direction ratios are the angles a line makes with the positive coordinate axes.

• Direction ratios are any numbers proportional to direction cosines.

• Direction ratios are \[\cos\alpha\], \[\cos\beta\], and \[\cos\gamma\].

• Direction ratios always satisfy \[a^{2}+b^{2}+c^{2}=1\].

Answer 1

Direction ratios need only be proportional to the direction cosines. Unlike direction cosines, direction ratios do not necessarily have squares whose sum is \[1\].