def in 8.md

There is 
```lean
def ConstructibleAngle (θ : ℝ) : Prop :=
  Constructible (Real.cos θ)
```

and
```lean
def ConstructibleAngle (cfg : RCBase) (θ : ℝ) : Prop :=
  ∃ P : Point, RCPoint cfg P ∧ baseAngle cfg P = θ
```

Is this causes some defination overload issue here?