BITSAT2020MathematicsVector AlgebraActual
If r and s arenon-zero constant vectors and the scalar b is chosen such that | r +b s | is minimum, then the value of |b s |²+| r +b s |² is equal to
Options
- A2| r |²
- B| r |² / 2
- C3| r |²
- D| r |²
Correct answer
D. | r |²
Step-by-step solution
For minimum value | r +b s |=0 . Let r and s are anti-parallel so b s =- r |b s |²+| r +b s |²=|- r |²+| r - r |²=| r |²