cos(-19π/4)的值
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cos(-19π/4)的值cos(-19π/4)的值cos(-19π/4)的值cos(-19π/4)=cos(19π/4)=cos[4π+3π/4]=cos(3π/4)=cos[π-π/4]=-cos
cos(-19π/4)的值
cos(-19π/4)的值
cos(-19π/4)的值
cos(-19π/4)
=cos(19π/4)
=cos[4π+3π/4]
=cos(3π/4)
=cos[π-π/4]
=-cos(π/4)
=-√2/2
cos(-19π/4)
=cos(19π/4)
=cos(19π/4-4π)
=cos(3π/4)
=cos(π/2+π/4)
=-sinπ/4
=-√2/2.
cos(-19π/4)的值
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