Direction ratios for a line in the form ax−x0=by−y0=cz−z0 are (a,b,c).
Line (A): 2x−1=12−y=z
Rewrite 12−y:
12−y=1−(y−2)
=−1y−2
Rewrite z as 1z−0
The line becomes:
2x−1=−1y−2=1z−0
Direction Ratios: (2,−1,1) which is (III)
Line (B): 22x−1=3y+1=11−z
Simplify 22x−1:
22x−1=22(x−21)
=1x−21
Rewrite 11−z:
11−z=1−(z−1)
=−1z−1
The line becomes:
1x−21=3y+1=−1z−1
Direction Ratios: (1,3,−1) which is (I)
Line (C): 2x+1=23−y,z=2
Rewrite 23−y:
23−y=2−(y−3)
=−2y−3
Since z=2 is constant, the line doesn't move in the z-direction.
Write as: 0z−2
The line becomes:
2x+1=−2y−3=0z−2
Direction Ratios: (2,−2,0) which is (II)
Line (D): 42x−3=21−2y=5z
Simplify 42x−3:
42x−3=42(x−23)
=2x−23
Simplify 21−2y:
21−2y=2−2(y−21)
=1−(y−21)
=−1y−21
Rewrite 5z as 5z−0
The line becomes:
2x−23=−1y−21=5z−0
Direction Ratios: (2,−1,5) which is (IV)
Final Matching:
(A) → (III)
(B) → (I)
(C) → (II)
(D) → (IV)