27.giúp với ạ

Question

giải pt:
$sin^{2}\frac{3}{2}x+sin^{2}(\frac{\pi }{4}-\frac{5}{2}x)=sin^{2}\frac{11}{2}x+sin^{2}(\frac{\pi }{4}-\frac{13}{2}x)$

score 0 · Answer 1

PT $\Leftrightarrow 1-cos3x +1-cos(\frac{\pi}{2}-5x)=1-cos11x+1-cos(\frac{\pi}{2}-13x)$

$\Leftrightarrow cos3x+sin5x=cos11x+sin13x$

$\Leftrightarrow cos11x-cos3x+sin13x-sin5x=0$

$\Leftrightarrow -sin7xsin4x+cos9xsin4x=0$

$\Leftrightarrow sin4x(cos9x-cos(\frac{\pi}{2}-7x))=0$

Đến đây okey

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