(x+ 30 độ ) = $\frac{\sqrt{3}}{2}$ 0 < x < 180 độ .các nghiệm là

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(x+ 30 độ ) = $\frac{\sqrt{3}}{2}$ 0 < x < 180 độ .các nghiệm là

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Môn Toán Calantha 4 years 2020-10-13T10:38:25+00:00 2020-10-13T10:38:25+00:00 2 Answers 114 views 0

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Captcha* Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )

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Dulcie · Answer 1 · 2020-10-13T10:39:38+00:00

Dulcie

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2020-10-13T10:39:38+00:00 October 13, 2020 at 10:39 am

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Đáp án:

$x = {30^{o}; 120^{0}}$

Giải thích các bước giải:

$\begin{array}{l} \sin (x + 30^{o}) = \frac{\sqrt{3}}{2} \\ \Leftrightarrow \sin (x + 30^{o}) = \sin 60^{o} \\ \Leftrightarrow [\begin{matrix} x + 30^{o} = 60^{o} + k {.360}^{o} \\ x + 30^{o} = 120^{o} + k {.360}^{o} \end{matrix} \\ \Leftrightarrow [\begin{matrix} x = 30^{o} + k {.360}^{o} \\ x = 90^{o} + k {.360}^{o} \end{matrix} (k \in Z) \\ T a c ó : \\ 0 < x < 180^{o} \\ \Leftrightarrow [\begin{matrix} 0 < 30^{o} + k {.360}^{o} < 180^{o} \\ 0 < 90^{o} + k {.360}^{o} < 180^{o} \end{matrix} \\ \Leftrightarrow [\begin{matrix} - \frac{1}{12} < k < \frac{5}{12} \\ - \frac{1}{4} < k < \frac{1}{4} \end{matrix} \\ \Rightarrow [\begin{matrix} k = 0 \\ k = 0 \end{matrix} (k \in Z) \\ \Rightarrow [\begin{matrix} x = 30^{o} \\ x = 120^{o} \end{matrix} \\ V ậ y x = {60^{o}; 120^{0}} \end{array}$

quangkhai · Answer 2 · 2020-10-13T10:40:24+00:00

quangkhai

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2020-10-13T10:40:24+00:00 October 13, 2020 at 10:40 am

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