
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 vectors $\overrightarrow {m}$=（cosα，sinα）, $\overrightarrow {n}$=（-1，2）
(1) If $\overrightarrow {m}$ is parallel to $\overrightarrow {n}$, find the value of $\frac {sinα-2cosα}{sin\alpha +cos\alpha }$;
(2) If $| \overrightarrow {m} - \overrightarrow {n}|= \sqrt {2}$, α∈$( \frac {π}{2}，π)$, find the value of tanα.

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