Question

Решить тригонометрическое уравнение

Answer 1

 $sqrt{2} -2 sqrt{2} sin^2 frac{15 pi }{8} =sqrt{2}(1 -2 sin^2 frac{15 pi }{8})=sqrt{2} cosfrac{15 pi }{4}=sqrt{2} cos( 2pi +frac{7 pi }{4})=sqrt{2} cos( frac{7 pi }{4})=sqrt{2} cos( 2 pi -frac{pi }{4})=sqrt{2}cosfrac{pi }{4}= sqrt{2}frac{ sqrt{2} }{2} =1$