Question

$sin(3x - \pi \div 4) = - \sqrt{2} \div 2$
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Answer 1

$sin(3x-\frac{\pi}{4} )=-\frac{\sqrt{2}}{2}$

$sin(-(\frac{\pi }4-3x) )=-\frac{\sqrt{2}}{2}\\sinx=-\frac{\sqrt{2}}{2} \\arcsin(-\frac{\sqrt{2}}{2})=\frac{7\pi }4$