cos(x-90)=cos(90-x)=sinx= √2/10
∴sinx=√2/10cos(X-45)=根号2/10，X属于90到135度，求sinx和sin（2x+60）=cos(x-45)=cosxcos45+sinxsin45=(cosx+sinx)√2/2=√2/10∴cosx+sinx=1/5(1) sin²x+cos²x=12sinxcosx=-24/25sin2x=-24/25cos2x=-7/25sin(2x+60)=sin2xcos60+cos2xsin60 =-12/25-7√3/50由(1)得cosx=1/5-sinx代入sin²x+cos²x=1得2sin²x-2sinx/5-24/25=025sin²x-10sinx-12=0太烦了