
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 curve C is: $$\begin{cases} \overset{x=1+ \sqrt {7}\cos\theta }{y= \sqrt {7}\sin\theta }\end{cases}(\theta\text{ is the parameter})$$, with O as the pole and the non-negative half-axis of x as the polar axis, a polar coordinate system is established.  
(Ⅰ) Find the polar equation of curve C;  
(Ⅱ) Given the line $l_1: 2\rho\sin(\theta+ \frac {\pi}{3})- \sqrt {3}=0$, and the ray $l_{2}: \theta= \frac {\pi}{3}(\rho＞0)$ intersect curve C at point P, and $l_{2}$ intersects line $l_{1}$ at point Q, find the length of segment PQ.

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