已知cos(π/6-a)=1/3,则cos(5π/6+a)sin(2π/3-a=?
已知cos(π/2+a)=2sin(a-π/2)求sin(π-a)+cos(a+π)/5cos(5π/2-a)+3sin
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已知a为第三象限角,且f(a)=sin(5π-a)cos(a+3π/2)cos(π+a)/sin(a-3π/2)cos(
已知 sin a-cos a=1/2,则 sin^3 a-cos^3 a
已知(4sin a-2cos a)/(5cos a +3sin a)=6/11,求cos^4 a-sin^4 a
已知2sin(a/2)=cos(a/2),则sin(a+π/6)=
急::已知sin(3π+a)=2cos(a-4π),求(5sin(π/2+a)+cos(π/2-a))/(2cos(π+
已知sin(a-π/3)=1/3,则cos(π/6+a)的值为?
已知sin(6/π+a)=1/3,则cos(π/3-a)的值是
已知sin(π/6+a)=1/3则cos(π/3-a)的值
已知sin(π/3-a)=1/2,求cos(π/6+a)的值
已知f(a)=sin (π-a )cos(2π-a )cos(-a+3/2π)/cos (π/2-a )sin (-π-