Question

if a cross b is equals to zero and a dot b is equals to minus ab then angle between vector a and vector b is​

Answer 1

Answer:

180°

Explanation:

a × b = 0  ⇒ absin(Ф) = 0         ( where Ф is the angle between a and b)

                So, sin(Ф) = 0  ⇒ Ф = 0° or 180°

a.b = -ab   ⇒ abcos(Ф) = -ab  

              by cancelling ab from both LHS and RHS

               we get cos(Ф) = -1   ⇒  Ф = 180°