Find a line-plane angle and reflect a point

Plane Π has equation $\mathbf r\cdot(1,2,-3)=5$. Line l passes through P with position vector $(7,4,−6)$ and is parallel to $(7,3,−5)$.

(i) Find the perpendicular distance from the origin to Π.3 marks

(ii) Find the acute angle between l and Π.3 marks

(iii) Find the position vector of the perpendicular foot from P to Π. Hence find the position vector of P’s reflection in Π.6 marks