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  1. By considering

    tan⁡(A+B)=tan⁡A+tan⁡B1−tan⁡Atan⁡B

    when A=x and B=x, prove that

    tan⁡(2x)=2tan⁡x1−tan2⁡x
  2. Hence, or otherwise, solve the equation

    tan⁡xtan⁡2x=1,0<x<π