“θ=2π/3”是“tanθ=2cos(π/2+θ)”的A.充分不必要条件B.必要不充分条件C.充要条件D.既不充分又不必要条件解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!解答过程!谢谢!