
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 $\overrightarrow {a} = (\sin\theta, \cos\theta - 2\sin\theta)$ and $\overrightarrow {b} = (1, 2)$.  
(1) If $\overrightarrow {a} \parallel \overrightarrow {b}$, find the value of $\tan\theta$;  
(2) If $|\overrightarrow {a}| = |\overrightarrow {b}|$ and $0 < \theta < \pi$, find the value of $\theta$.

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