A line makes angles of 45° and 60° with the positive axes of x and y respectively. What angle does it make with the positive axis of z?
The given points are A(2, 3, – 4), B(1, –2, 3), C(3, 8, –11)
The direction ratios of the AB are 1 – 2, – 2 – 3, 3 + 4 i.e. – 1 – 5,1
The direction ratios of AC are 3 – 2, 8 – 3, –11 + 4 i.e. 1, 5, – 7
∴ direction ratios of AB and AC are proportional
∴ AB is parallel to AC.
But A is a common point on both the lines.
∴ A, B, C are collinear points.
Find the length of the projection of the line segment joining the points P (3, -1, 2) and Q(2, 4, -1) on the line with direction ratios -1, 2, -2.