已知x^2+y^2=1,z^2+w^2=1,xz+yw=0,求xy+zw的值
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已知x^2+y^2=1,z^2+w^2=1,xz+yw=0,求xy+zw的值
我不会,帮一下啦
我不会,帮一下啦
![已知x^2+y^2=1,z^2+w^2=1,xz+yw=0,求xy+zw的值](/uploads/image/z/14920094-38-4.jpg?t=%E5%B7%B2%E7%9F%A5x%5E2%2By%5E2%3D1%2Cz%5E2%2Bw%5E2%3D1%2Cxz%2Byw%3D0%2C%E6%B1%82xy%2Bzw%E7%9A%84%E5%80%BC)
令x=cosa y=sina
z=cosb w=sina
xz+yw=cos(a-b)=0
a-b=π/2
xy+zw=sina*cosa+sinb*cosb
=(sin2a+sin2b)/2
=(sin2a+sin(2a-π))/2
=0
z=cosb w=sina
xz+yw=cos(a-b)=0
a-b=π/2
xy+zw=sina*cosa+sinb*cosb
=(sin2a+sin2b)/2
=(sin2a+sin(2a-π))/2
=0
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