The assumptions don’t get used and mathematica lacks 3-D vector functions?

How can I get the results that I want in a numeric form?

I want to find the angle between a and b it should be near 90 degrees.

```
$ Assumptions = {a, e, b} \[Element] Vectors[3, Reals] &&
a.a == b.b == 156 && e.e == 1 &&
a.e == b.e == 90 &&
p == a - (a.e) e &&
q == b - (b.e) e
Simplify[Dot[a, b]
dotAB = (p + (a.e) e).(q + (b.e) e)
Simplify[TensorExpand[%]]
(*want p.q +(a.e)(b.e) since*)
(*a.e)e.q =p.e (a.e)\[Equal]0*)
(*a.b should be equal to -17.93*)
```