已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3π/4 β)=5/13,

已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3π/4+β)=5/13,求sina(α+β)的值已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3

已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3π/4+β)=5/13,求sina(α+β)的值已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3

已知0＜β＜π/4＜α＜3π/4,cos(π/4+α)=3/5,sina(3π/4+β)=5/13,求sina(2α+2β)的值已知0＜β＜π/4＜α＜3π/4,cos(π/4+α)=3/5,sina

已知0＜β＜π/4＜α＜3π/4,cos(π/4+α)=3/5,sina(3π/4+β)=5/13,求sina(2α+2β)的值已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina

已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina(3π/4+β)=5/13,求cos(α-β﹚帮帮忙啊!已知0＜β＜π/4＜α＜3π/4,cos(π/4-α)=3/5,sina

已知π/4已知sina=4根号3/7,cos(a-β),且0已知π/4已知sina=4根号3/7,cos(a-β),且0已知π/4已知sina=4根号3/7,cos(a-β),且0∵π/4

已知cos(a-π/6)=4/5(π/6＜a＜2π/3)求sina的值已知cos(a-π/6)=4/5(π/6＜a＜2π/3)求sina的值已知cos(a-π/6)=4/5(π/6＜a＜2π/3)求s

已知sina=4/5(π/2＜a＜π）cos(a-β）=5/13（3π＜a-β＜2π）求cosβ的值已知sina=4/5(π/2＜a＜π）cos(a-β）=5/13（3π＜a-β＜2π）求cosβ的值

①已知Sina+COSa/Sina-COSa=3,求Sina,COSa的值；②已知π/2＜b＜a＜3π/4,COS（a-b)=12/13②已知π/2小于b＜a＜3π/4,COS（a-b)=12/13,

已知2sina/2·cos(π/2-a/2)=3/4,求sina已知2sina/2·cos(π/2-a/2)=3/4,求sina已知2sina/2·cos(π/2-a/2)=3/4,求sina2sin

已知向量a=（cosa,sina）,向量b=（cosβ,sinβ）,若-π/4＜a＜π/4,β=π/4,且且a点乘b=3/5,求sina已知向量a=（cosa,sina）,向量b=（cosβ,sinβ

已知sina=3/5a∈(π/2,π)求cos(π/4-a)已知sina=3/5a∈(π/2,π)求cos(π/4-a)已知sina=3/5a∈(π/2,π)求cos(π/4-a)cosa=-4/5c

已知sina=2/3,cosβ=-3/4,α∈(π/2,π),β∈(π,3π/2),求cos(α-β)的值已知sina=2/3,cosβ=-3/4,α∈(π/2,π),β∈(π,3π/2),求cos(

已知a为锐角,且cos（a+π/4）=-3/5,求sina已知a为锐角,且cos（a+π/4）=-3/5,求sina已知a为锐角,且cos（a+π/4）=-3/5,求sinaα为锐角,cos(α+π/

已知sina=-3/5,且π/2＜a＜π,求cos（2a-π/4）的值要过程已知sina=-3/5,且π/2＜a＜π,求cos（2a-π/4）的值要过程已知sina=-3/5,且π/2＜a＜π,求co

已知0＜α＜π,sin(α+π/4)=12/13,求sina/cos(π/4-α)的值已知0＜α＜π,sin(α+π/4)=12/13,求sina/cos(π/4-α)的值已知0＜α＜π,sin(α+

已知sin(a+Kπ)=-2cos（a+Kπ）,K∈Z则4sina-2coxa/5cosa+3sina已知sin(a+Kπ)=-2cos（a+Kπ）,K∈Z则4sina-2coxa/5cosa+3si

已知sina=1/3,则sin(a+π/4)cos(a+π/4)已知sina=1/3,则sin(a+π/4)cos(a+π/4)已知sina=1/3,则sin(a+π/4)cos(a+π/4)sin(

已知cos(a-π/6）+sina=4根号下3/5,则sin(a+7π/6)=?已知cos(a-π/6）+sina=4根号下3/5,则sin(a+7π/6)=?已知cos(a-π/6）+sina=4根

已知cos（a-π/6）+sina=4√3/5,则sin(a+7π/6)=?已知cos（a-π/6）+sina=4√3/5,则sin(a+7π/6)=?已知cos（a-π/6）+sina=4√3/5,