The answer "3pi/2" in the post by @lwsshak3 is INCORRECT.
This problem is a simple elementary , and @lwsshak3 fell in this trap.
To answer correctly, you should remember that function arccos has values in interval [,].
Therefore, you should transform to the equivalent angle in interval [,].
This equivalent angle is , so the correct answer to the problem's question is .
Solved correctly, while the "solution" by @lwsshak3 is disproved.
This problem is a simple elementary . It provokes you to answer " ", but this answer is WRONG.
To answer correctly, you should remember that function arccos has values in interval [,].
Therefore, you should transform to the equivalent angle in interval [,].
This equivalent angle is , so the correct answer to the problem's question is .
Solved.
Be accurate and attentive in order for do not fall in this and similar traps.
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