Question

If the co-ordinates of A and B be (1, 2, 3) and (7, 8, 7), then the projections of the line segment AB on the co-ordinate axes are

• A. 6, 6, 4
• B. 4, 6, 4
• C. 3, 3, 2
• D. 2, 3, 2

Answer 1

Answer: (A)

6, 6, 4

Answer 2

Here, $x _ { 2 } - x _ { 1 } = 6$, $y _ { 2 } - y _ { 1 } = 6$ , $z _ { 2 } - z _ { 1 } = 4$ and d.c's of $x , y , z$ -axes are (1,0,0), (0,1,0), (0, 0, 1) respectively.

Now projection = $\left( x _ { 2 } - x _ { 1 } \right) l + \left( y _ { 2 } - y _ { 1 } \right) m + \left( z _ { 2 } - z _ { 1 } \right) n$

$\therefore$Projections of line AB on co-ordinate axes are 6, 6, 4 respectively.