Sin(2α+π/2),α∈（π,3π/2）用诱导公式怎么求?RT,一般的诱导公式比如Sin(α+π/2),α∈（π,3π/2）我会求,但是变成2α用诱导公式怎么求?要是也遵循奇变偶不变符号看象限的话2α不就在（2π,3π）,也

化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)= 2sin(α+π/3）=sinα+______ 已知sin(3π-α)=-2sin(π/2+α)则sinαcosα 求sin^2α+sin^2(π/3 +α)+sin^2(π/3 -α) 设α,β,γ∈(0,π/2)且(sinα)^2+(sinβ)^2+(sinγ)^2=1求函数y=(sinα)^3/sinβ+(sinβ)^3/sinγ+(sinγ)^3/sinα 的最小值. 若α∈(π/2,π),sin(α+π/6)=3/5,sinα= ①利用公式sin(π-θ)=sinθ和sin(∏+θ)=-sinθ证明：sin（-θ）=-sinθ②证明tanθsinθ∕tanθ-sinθ=1+cosθ∕sinθ③已知sinα-2cosα+1=0,α≠kπ+π∕2,k∈z求：tan（3π-α）和1∕sin2α-sinαcosα+1的值‍ 已知6sin²α+sinαcosα-2cos²α=0,α∈（π/2,π）,求值1).(sinα-3cosα）/（sinα-cosα）；2）.sinαcosα-sin²α;3).sin²α-3cosαsinα-2 为什么sin(2π-α)=-sinα? 化简sin(-π/2-α)sin(πα)cos(-α-π)/cos(π-α)sin(3π α) 求值【sin(2π-α)sin(π+α)cos(-π-α)】/【sin(3π-α)-cos(π-α)】 sin(π-α)=-2sin(π/2+α),则sinαcosα等于 sin(π-α)=-2sin(π/2+α),求sinα·cosα 已知β∈[-π/6,π/4）,且3（sinα）^2-2（sinβ）^2=2sinα,求（sinβ）^2-1/2sinα的最小值 化简:sin(2π-α)cos(π+α)cos(11π/2-α)/cos(π-α)sin(3π-α)sin(-π-α)sin(9π/2+α) 化简sin^2(α-π/6)+sin^2(α+π/6)-sin^2α 求值sin^2(α-π/6)+sin^2(α+π/6)-sin^2α 计算,sin(π/12)-sin(5π/12)+2sin(π/8)sin(3π/8)