
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
It is known that the terminal side of angle $α$ intersects with the unit circle at point $P\left( \dfrac {4}{5}, \dfrac {3}{5}\right)$.
(I) Find the values of $\sin α$, $\cos α$, and $\tan α$.
(II) Find the value of $\left(\sin \dfrac {α}{2}-\cos \dfrac {α}{2}\right)^{2}$.

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