Question

What is the angle between vector PQ and the positive x-axis, given endpoints P(4, 7) and Q(8, 3)?

Answer 1

The angle is `=3/4pi+kpi` , `AA k in ZZ`

Explanation:

The point P is `((4),(7))`

The point Q is `((8),(3))`

The vector `vec(PQ)=Q-P=((8),(3))-((4),(7))=((8-4),(3-7))=((4),(-4))`

The angle is

`theta= arctan(-4/4)=arctan(-1)=3/4pi+kpi` , `AA k in ZZ`