InterviewSolution
Saved Bookmarks
| 1. |
If a+b+c=0 and |a|=5, |b|=3 and |c|=7, then angle between a and b is |
|
Answer» `pi/2` `impliesa+b=-c` On squaring both SIDES, we get `(a+b)^(2)=(-c)^(2)IMPLIES|a+b|^(2)=|c|^(2)` `implies|a|^(2)+|b|^(2)+2a*b=|c|^(2)` `[because theta` be the ANGLE between a and b] `implies(5)^(2)+(3)^(2)+2|a||b|cos theta =(7)^(2)` `implies25+9+2.5.3cos theta =49` `implies30 cos theta =15` `implies cos theta =1/2=cos 60^(@)` `impliestheta =(pi)/(3)` |
|