求证sin(3π/2-a)=-cosa

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求证sin(3π/2-a)=-cosa求证sin(3π/2-a)=-cosa求证sin(3π/2-a)=-cosasin(3π/2-a)=sin(π+π/2-a)=-sin(π/2-a)=-cosas

求证sin(3π/2-a)=-cosa
求证sin(3π/2-a)=-cosa

求证sin(3π/2-a)=-cosa
sin(3π/2-a)=sin(π+π/2-a)=-sin(π/2-a)=-cosa

sin(3π/2-a)
=sin(3π/2)cosa-cos(3π/2)sina
=-1×cosa-0×sina
=-cosa