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

Explanation

Since `vecR` is perpendiuclar to `vecA`.
fig shows the three vectors `vecA,vecB` and `vecR`.
angle between `vecA` and `vecB` is `pi-theta`
`sintheta=(R)/(B)=(B)/(2B)=(1)/(2)`

`rArr theta=30^(@)`
`rArr` angle between `vecA` and `vecB` is `150^(@)`