已知sinx+cosx=1/2,求cos²(π/4+x)+sin2x的值
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已知sinx+cosx=1/2,求cos²(π/4+x)+sin2x的值
已知sinx+cosx=1/2,求cos²(π/4+x)+sin2x的值
已知sinx+cosx=1/2,求cos²(π/4+x)+sin2x的值
sinx+cosx = 1/2
(sinx+cosx)^2 = 1/4
sin^2x+cos^2+2sinxcosx = 1/4
1 +sin2x = 1/4
sin2x = -3/4