Question

Tìm nghiệm của các phương trình sau:

a) \(2sin\left(50^o-3x\right)+1=0\)

b) \(sinx+\frac{\sqrt{3}}{2}=0\)

Answer 1

a/ \(\Leftrightarrow sin\left(50^0-3x\right)=-\frac{1}{2}=sin\left(-30^0\right)\)

\(\Rightarrow\left[{}\begin{matrix}50^0-3x=-30^0+k360^0\\50^0-3x=210^0+k360^0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{80^0}{3}+k120^0\\x=-\frac{160^0}{3}+k120^0\end{matrix}\right.\)

b/ \(\Leftrightarrow sinx=-\frac{\sqrt{3}}{2}=sin\left(-60^0\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-60^0+k360^0\\x=240^0+k360^0\end{matrix}\right.\)