求sin（2nπ＋2π/3)·cos(nπ＋4π／3)的值（nεZ）
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1)当n为偶数时， sin(2nπ+2π/3)+cos(nπ+4π/3)=sin2π/3+cos4π/3)
=sin(π-π/3)+cos(π+π/3).
=sinπ/3-cosπ/3
=sinπ/3-cosπ/3.
=√3/2-1/2
2）当n为奇数时，sin(2nπ+2π/3)+cos(nπ+4π/3)=sin2π/3-cos4π/3.
=√3/2-(-1/2).
=√3/2+1/2.
=sin(π-π/3)+cos(π+π/3).
=sinπ/3-cosπ/3
=sinπ/3-cosπ/3.
=√3/2-1/2
2）当n为奇数时，sin(2nπ+2π/3)+cos(nπ+4π/3)=sin2π/3-cos4π/3.
=√3/2-(-1/2).
=√3/2+1/2.
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