
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, the equation of line $l$ is $x+y+3=0$. In the polar coordinate system with the positive half-axis of the x-axis as the polar axis, the polar equation of circle $M$ is $\rho=2\sin\theta$.  
(Ⅰ) Write the Cartesian coordinate equation of circle $M$ and the parametric equation of the line $l_1$ that passes through point $P(2,0)$ and is parallel to $l$;  
(Ⅱ) Suppose the two intersection points of $l_1$ with circle $M$ are $A$ and $B$, calculate the value of $\frac {1}{PA} + \frac {1}{PB}$.

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