Let \( A(\alpha,-2), B(\alpha,6) \) and \( C\!\left(\dfrac{\alpha}{4},-2\right) \) be vertices of a \( \triangle ABC \). If \( \left(5,\dfrac{\alpha}{4}\right) \) is the circumcentre of \( \triangle ABC \), then which of the following is NOT correct about \( \triangle ABC \)?
