
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In the Cartesian coordinate system $xOy$, the parametric equation of $C_{1}$ is $\begin{cases} x=t\cos \alpha \\ y=-1+t\sin \alpha \end{cases}$ (where $t$ is the parameter, $0\leqslant \alpha < \pi$). In the polar coordinate system with the origin $O$ as the pole and the positive $x$-axis as the polar axis, the polar equation of $C_{2}$ is $\rho=2 \sqrt {2}\cos (\theta- \frac {\pi}{4})$.
(Ⅰ) Find the Cartesian coordinate equation of $C_{2}$ and describe the shape of its graph;
(Ⅱ) $C_{1}$ intersects with $C_{2}$ at two distinct points $A$ and $B$, the midpoint of segment $AB$ is $M$, and point $N(0,-1)$. If $|MN|=2$, find the value of $\sin \alpha$ in the parametric equation of $C_{1}$.

Present the answer in LaTex format: \boxed{Your answer}
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