If a line makes angles 90°, 135°, 45° with x, y and z-axes respectively, find its direction cosines.

Find the direction cosines of a line which makes equal angles with the coordinate axes.

If a line has the direction ratios −18, 12, −4, then what are its direction cosines?

Show that the points (2, 3, 4), (−1, −2, 1), (5, 8, 7) are collinear.

The vertices of ΔABC are A (3, 5, −4), B (−1, 1, 2), and C (−5, −5, −2).