Question

已知cos(x加2分之派)等于负3分之一求tan2x

Answer 1

问：已知cos(x加2分之派)等于负3分之一求tan2x

答：你好，结果为4√2/7

答：拓展

答：三角函数转换公式:sin(-α)= -sinα;cos(-α) = cosα;sin(π/2-α)= cosα;cos(π/2-α) =sinα;sin(π/2+α) = cosα;cos(π/2+α)= -sinα;sin(π-α) =sinα;cos(π-α) = -cosα;sin(π+α)= -sinα;cos(π+α) =-cosα;tanA= sinA/cosA;tan(π/2+α)=-cotα;tan(π/2-α)=cotα;tan(π-α)=-tanα;tan(π+α)=tanα。