To solve the inequality sin x ā ( cos x + 2 3 ā ā ) ⤠0 , we identify that sin x ā ā„ 0 and solve for cos x ⤠ā 2 3 ā ā . The final intervals where both conditions overlap are [ 6 5 Ļ ā , 6 7 Ļ ā ] + 2 nĻ for integers n .
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To solve the inequality sin x ā ( cos x + 2 3 ā ā ) ⤠0 , we should consider each factor separately and understand where the inequality could hold true.
Understanding sin x ā :
The expression sin x ā is defined only when sin x ā„ 0 , because you cannot have a square root of a negative number.
sin x ā„ 0 is true in the intervals where x = kĻ to x = kĻ + Ļ , where k is an integer. Specifically, in the range 0 ⤠x ā¤ Ļ and repeating every 2 Ļ .
Understanding cos x + 2 3 ā ā :
The expression cos x + 2 3 ā ā ⤠0 implies cos x ⤠ā 2 3 ā ā .
The cosine function is less than or equal to ā 2 3 ā ā in certain sections of its cycle, specifically between the angles where x = 5 Ļ /6 and x = 7 Ļ /6 within a 0 ⤠x ⤠2 Ļ interval, and these intervals repeat every 2 Ļ .
Combining the Conditions:
Now we need both conditions to be true simultaneously.
For sin x ā„ 0 and cos x ⤠ā 2 3 ā ā , this is satisfied on the interval 5 Ļ /6 ⤠x ā¤ Ļ on a single cycle.
Conclusion:
Considering the periodic nature of trigonometric functions, the inequality holds for x in the intervals 6 5 Ļ ā + 2 kĻ ā¤ x < Ļ + 2 kĻ for integer k .
Thus, the solution sets for the inequality occur at certain intervals depending on the periodicity and defined regions for sin x ā and cos x + 2 3 ā ā . These mathematical details ensure the inequality is understood and interpreted correctly.