化简 sin(π+α)+sin(2π+α)+sin(3π+α)+……+sin(kπ+α) k属于Z

化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)= 化简sin^2(α-π/6)+sin^2(α+π/6)-sin^2α sin(kπ+α)化简 2sin(α+π/3）=sinα+______ 为什么sin(2π-α)=-sinα? 化简sin(-π/2-α)sin(πα)cos(-α-π)/cos(π-α)sin(3π α) 化简 {sin(π+α)cos(α-2π)tan9π/4}/sin(-α)sin(7π/2+α)过程 化简sin(π/4+α)cosα-sin(π/4-α)sinα 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1－sin[α－2π]sin[π＋α]－2sin²[－α]. 化简：sin²α+sin²（α+π/3）+sin²（α-π/3） sin(π-α)=-2sin(π/2+α),则sinαcosα等于 sin(π-α)=-2sin(π/2+α),求sinα·cosα 已知sin(3π-α)=-2sin(π/2+α)则sinαcosα 求sin^2α+sin^2(π/3 +α)+sin^2(π/3 -α) 求值sin^2(α-π/6)+sin^2(α+π/6)-sin^2α 化简 sin(π+α)+sin(2π+α)+sin(3π+α)+……+sin(kπ+α) k属于Z 化简:(sinα-cosα)^2+sin4α/2cos2α 化简:sin^2x+sin^2(x+2π/3)+sin^2(x-2π/3)