Saved Bookmarks
| 1. |
Find |x|, if for a unit vector a, (vec(x)-vec(a)).(vec(x)+vec(a))=12. |
|
Answer» SOLUTION :Given, `|a|=1`. (`because` It is a UNIT vector, magnitude of a unit vector is 1.) and `(VEC(x)-vec(a)).(vec(x)+vec(a))=12` `RARR vec(x).vec(x)+vec(x).vec(a)-vec(a).vec(x)-vec(a).vec(a)=12 ( because a.a =|a|^2 and a.b =b.a)` `|vec(x)|^2-|vec(x)|^2=12 rArr |vec(x)|-12=12 [because |a|=1 "as a is a unit vector"]` `rArr |vec(x)|^2=13 rArr |vec(x)|=sqrt(13)`. |
|