
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
 $ AA_{3}$  and  $ BB_{3}$  are altitudes of acute-angled  $ \triangle ABC$ . Points  $ A_{1}$  and  $ B_{1}$  are second points of intersection lines  $ AA_{3}$  and  $ BB_{3}$  with circumcircle of  $ \triangle ABC$  respectively.  $ A_{2}$  and  $ B_{2}$  are points on  $ BC$  and  $ AC$  respectively.  $ A_{1}A_{2}\parallel AC$ ,  $ B_{1}B_{2}\parallel BC$ . Point  $ M$  is midpoint of  $ A_{2}B_{2}$ .  $ \angle BCA \equal{} x$ . Find  $ \angle A_{3}MB_{3}$ .

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