
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
Given that $\frac {π}{2}＜α＜ \frac {3π}{2}$, points A, B, and C are in the same plane rectangular coordinate system with coordinates A(3, 0), B(0, 3), and C(cosα, sinα) respectively.
(1) If $| \overrightarrow {AC}|=| \overrightarrow {BC}|$, find the value of angle α;
(2) When $\overrightarrow {AC}\cdot \overrightarrow {BC}=-1$, find the value of $\frac {2sin^{2}α+sin(2α)}{1+tan\alpha }$.

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