Question

if |A-B| = |A|-|B|, the angle between A and B is? explain plz
​

Answer 1

given that

|A-B|=|A|+B|

then we have

(A-B)^2 =(A+B)^2

the a square plus b square - 2ab=a square plus b square plus 2ab

then we have 4ab = 0

ab=0

then angle between a and b is

$\pi \div 2$