
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 the initial side of angle α is the non-negative half of the x-axis, and its terminal side passes through point P(m, -m-1), and $$cosα= \frac {m}{5}$$.
(1) Find the value of the real number m;
(2) If m > 0, find the value of $$\frac {sin(3π+α)cos( \frac {3π}{2}-α)}{cos(α-π)sin( \frac {π}{2}+α)}$$.

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