已知COS(2α-β)=-11/14 SIN(α-2β)=4倍根号3/7 且π/4<α<π/2,0<β<π/4 求COS
已知COS(2α-β)=-11/14 SIN(α-2β)=4倍根号3/7 且π/4<α<π/2,0<β<π/4 求COS
已知sin(3π-α)=根号2倍的sinβ,根号3倍的cos(-α)=-根号2倍的cos(π+β),0<α<π
已知sin(3π-α)=根号二cos(3π/2+β),根号三cos(-α)=负根号二cos(π+β),且0
已知0<α<π/2,且3sinα=4cosα求(sin^2α+2sinαcosα)/(3cos^2α-1)求cos^2α
已知sinα=根号2sinβ,根号3cosα=根号2cosβ,且0<α,β<π,求α和β的值.
已知sin(5π-α)=根号2×cos[(2÷7)+β]和根号3×cos(-α)=根号2×cos(π+α),且0<α<π
已知sinα+cosα=三分之根号二,sinα-cosα=-4/3,且α∈(-π/2,0),计算(1+sin2α+cos
已知sin(3π-α)=根号2*sin(π-β),根号3*cos(-α)=-根号2*cos(π+β),且α、β∈(0,π
已知sin(3π-a)= 根号2sin(π-β),根号3cos(-a)= -根号2cos(π+β),且α β属于(0,π
已知α∈(0,π/2),且2sinα-sinαcosα-3cosα=0.求[sin(α+π/4)]/[sin2α+cos
已知α∈(0,π/2),且2sin²α-sinαcosα-3cos²α=0,求[sin(α+π/4)
已知cos(π/2-α)-2cosα=sinπ,且cosα<0,则sinα的值为?