sin^4 23п/12-cos^4 13п/12

оооо спасибо. ....

sin⁴(23π/12)-cos⁴(23π/12)=(sin²(23π/12)+cos²(23π/12))*(sin²(23π/12)-cos²(23π/12))=1*(sin²(23π/12)-cos²(23π/12))=-(cos²(23π/12)-sin²(23π/12))=-cos(2*(23π/12))=-cos(23π/6)=-cos(24π/6-π/6)=-cos(4π-π/6)=-cos(π/6)=-1/2