The number of marks is given in brackets [ ] at the end of each question or part question. 1 A plane $\pi_{1}$ contains two vectors $\left(\begin{array}{l}1 \ 1 \ 0\end{array}\right)$ and $\left(\begin{array}{r}1 \ -5 \ -2\end{array}\right)$.

(i) Find a vector normal to $\pi_{1}$.

[2]

A plane $\pi_{2}$ has equation $4 x+5 y-6 z=0$

(ii) Find the acute angle between $\pi_{1}$ and $\pi_{2}$.

[2]