Math
posted by Anonymous .
Two vectors 2a+b and a=3b are perpendicular. Find the angle between a and b, if a = 2b.

Is a = 3b supposed to be a  3b? or a + 3b?
If a = 3b is one of the vectors, then you would be saying that a and b are collinear, with a = 3b. That would contradict your later statement that a = 2b