Question

if vectors a and b are such that |A+B|=|A|=|B|,then |A-B|may be equated to​

Answer 1

hey mate

here is the answer..

A²=A²+B²+2AB cos ∆

and

B²=A²+B²+2AB cos ∆

thus,

0=B²+2ABcos ∆.....(i)

and

0=A²+2ABcos ∆.....(i i)

on adding equ..(i) and (i i)

0=A²+B²+4ABcos ∆

-2ABcos ∆=A²+B²+2AB cos ∆....equ(i i i)

Now,

|A-B|=√(A²+B²-2AB cos ∆)

from equ..(i i i)

|A-B|=√(A²+B²+A²+B²+2AB cos∆)

|A-B|=√(2(A²+B²+AB cos∆))