Question

Vectors A and B are such that A+B = A-B The angle between vectors is = ?

Answer 1

Answer:

We have

∣

∣

∣

∣

a

+

b

∣

∣

∣

∣

=

∣

∣

∣

∣

a

−

b

∣

∣

∣

∣

⇒

∣

∣

∣

∣

a

+

b

∣

∣

∣

∣

2

=

∣

∣

∣

∣

a

−

b

∣

∣

∣

∣

2

⇒

∣

∣

∣

∣

a

∣

∣

∣

∣

2

+

∣

∣

∣

∣

b

∣

∣

∣

∣

2

+2

a

.

b

=

∣

∣

∣

∣

a

∣

∣

∣

∣

2

+

∣

∣

∣

∣

b

∣

∣

∣

∣

2

−2

a

.

b

⇒

a

.

b

=0

∴

a

⊥

b

∴θ=90

∘

Hence, Angle btween two vector is 90

o

.