
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
Consider two points on the surface of a sphere, representing Earth. Point $A$ is located at $0^\circ$ latitude and $90^\circ \text{ E}$ longitude, and point $B$ is at $30^\circ \text{ N}$ latitude and $90^\circ \text{ W}$ longitude. Calculate the degree measure of $\angle ACB$ where $C$ is the center of the Earth.

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