Question

If (A + B) =(A-B) then the angle between the Ả and B.​

Answer 1

Angle between A and B is:-

Given:-(A+B)=(A-B)

The two formula to be used here are:-

• (A+B)=

$\ \sqrt{ {a}^{2} } + {b}^{2} + 2ab \cos( \alpha )$

• (A-B)=

$\sqrt{ {a}^{2} } + {b }^{2} - 2ab \cos( \alpha )$

since both these are equal

$\sqrt{ {a}^{2} } + {b}^{2} + 2ab \cos( \alpha ) = \sqrt{ {a}^{2} } + {b}^{2} - 2ab \cos( \alpha )$

$\sqrt{ {a}^{2} } + {b}^{2}$gets cancel on both sides.

$2ab \cos( \alpha ) = - 2ab \cos( \alpha )$

$4ab \cos( \alpha ) = 0$

$\cos( \alpha ) = 0$

$\alpha = 90 \: degree$

So, Angle between A and B is 90°.