.
- = -1 <====> (is equivalent to)
= 0 <====> (is equivalent to)
= 0 <====> (is equivalent to)
= 0 <====> (is equivalent to)
= 1 <====> (is equivalent to)
= +/- 1.
Case 1. = 1 is equivalent to = , , , . . . , , where n is any integer.
General solution for this case is = , where n is any integer.
Case 2. = -1 is equivalent to = , , , . . . , , where n is any integer.
General solution for this case is = , where n is any integer
Answer. Any angle of the set , is the solution, where k is any integer.
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