已知向量a=(cos3′5π,sin3′5π),b==(cos3′x,-sin3′x),x∈[0.2′π]
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![已知向量a=(cos3′5π,sin3′5π),b==(cos3′x,-sin3′x),x∈[0.2′π]](/uploads/image/z/4342261-13-1.jpg?t=%E5%B7%B2%E7%9F%A5%E5%90%91%E9%87%8Fa%3D%EF%BC%88cos3%E2%80%B25%CF%80%2Csin3%E2%80%B25%CF%80%EF%BC%89%2Cb%3D%3D%EF%BC%88cos3%E2%80%B2x%2C%EF%BC%8Dsin3%E2%80%B2x%EF%BC%89%2Cx%E2%88%88%5B0.2%E2%80%B2%CF%80%5D)
已知向量a=(cos3′5π,sin3′5π),b==(cos3′x,-sin3′x),x∈[0.2′π]
已知向量a=(cos3′5π,sin3′5π),b==(cos3′x,-sin3′x),x∈[0.2′π]
已知向量a=(cos3′5π,sin3′5π),b==(cos3′x,-sin3′x),x∈[0.2′π]
f(x)=cos(2x-π/3)+2sin(x-π/4)sin(x+π/4)
=cos2xcosπ/3+sin2xsinπ/3+2sin(x+π/4)cos(x+π/4)
=1/2cos2x+根3/2sin2x+sin(2x+π/2)
=3/2cos2x+根3/2sin2x
=根3(1/2sin2x+根3/2cos2x)
=根3(sin2xcosπ/3+cos2xsinπ/3)
=根3sin(2x+π/3)
最小正周期为π