已知sin(兀/4+x)=-3/5,则sin2x的值为?

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已知sin(兀/4+x)=-3/5,则sin2x的值为?

已知sin(兀/4+x)=-3/5,则sin2x的值为?
已知sin(兀/4+x)=-3/5,则sin2x的值为?

已知sin(兀/4+x)=-3/5,则sin2x的值为?
sin(π/4+x)=-3/5
sinxcosπ/4+cosxsinπ/4=-3/5
√2/2(sinx+cosx)=-3/5
sinx+cosx = -3√2/5
(sinx+cosx)^2 = (-3√2/5)^2
sin^2x+cos^2x+2sinxcosx=18/25
1+sin2x=18/25
sin2x = -7/25

sin(π/4+x)=-3/5 sinxcosπ/4+cosxsinπ/4=-3/5 √2/2(sinx+cosx)=-3/5 sinx+cosx = -3√2/5 (sinx+cosx)^2 = (-3√2/5)^2 sin^2x+cos^2x+2sinxcosx=18/25 1+sin2x=18/25 sin2x = -7/25