Question
If a line makes an angle of π/4 with the positive directions of each of x-axis and y-axis, then the angle that the line makes with the positive direction of the z-axis is
-
π/6
-
π/3
-
π/4
-
π/2
Solution
D.
π/2
l = cos π/4 , m = cos π/4
we know l2 + m2 + n2 = 1
Hence angle with the positive direction of z-axis is π/2 .