Помогите пож x-y = п cosy*sinx = 1/2

X-y=π⇒x=π+y
cosy*sinx=1/2
cosy*sin(π+y)=1/2
cosy*(-siny)=1/2
-1/2*sin2y=1/2
sin2y=-1
2y=-π/2
y=-π/4
x=π-π/4=3π/4
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cos(-π/4)*sin3π/4=cosπ/4*sinπ/4=√2/2*√2/2=2/4=1/2