The resultant of two vectors ` vecA and vecB ` is perpendicular to ` vecA ` . Magnitude of Resultant ` vecR ` is equal to half Magnitude of ` vecB ` . Find the angle between ` vecA and vecB `?

Explanation

Since `vecR` is perpendicular to `vecA` . figure shows the three vectors `vecA, vecB` and `vecR`
and angle between `vecA` and `vecB` is p-q

`sinq =R/B =B/(2B) =1/2`
`rArr q=30^(@) rArr` angle between A and B is `150^(@)`