已知cos(π+α)=-5/13,3π/2
已知cos(α+β)=12/13,cos(2α+β)=3/5,若β∈(0,π/2),求cosα的值.
已知cos(π+α)=-5/13,3π/2
已知α、β∈【0,π),tanα/2=2/3,cos(α+β)=5/13,求cosβ.
已知cos(π/2+α)=2sin(α-π/2),求[sin^3(π+α)+cos(α+π)]/[5cos(5π/2-α
已知cosα=1/3,α属于(π,2π),则cosπ/2等于
已知cos(π/2+α)=sin(α-π/2) 求sin(π-α)-cos(π+α)/cos(5π/2 -α)+2sin
已知tan(π+α)=1/3,求cos²(π+α)+sin(π+α)cos(π-α)-2cos²(3
①化简[sin(2π+α)*cos(7π-α)]/cos(-α)②已知cosθ=-3/5,θ∈(π/2,π),求sin(
已知(3sinα+cosα)/(3cosα-sinα)=2,则2-3sin(α-3π)sin(1.5π-α)-[cos(
已知cos(α-π/3)=12/13,α∈(π/3,π/2),求cosα
1.已知cosα=12/13,α∈(3π/2,2π),求cos(α+π/4).
已知cos(π\3-2)=1\3,则cosα+根号3sinα=