The vector equation of a line passing through point a and parallel to vector b is
- r = a × b
- r = a · b
- r = a + λb
- r = λa + b
Show answer and solution
Correct answer: C. r = a + λb
1. A line through point a in the direction of b is the set of all r reachable by moving from a along b.
2. The position vector is r = a + λb, where λ is the scalar parameter.
3. Varying λ traces the entire line.
4. So option C is correct.
_Source: syllabus Maths Part 2 Ch 11 "Three Dimensional Geometry", §11.3.1_