x=a(tanθ+1/cosθ)= a(sinθ+1)/cosθ= y*(sinθ+1)即 sinθ = x/y - 1又 y=a/cosθ 即 cosθ = a/y由sin²θ+cos²θ=1得(x/y - 1)² +a²/y² = 0(x-y)²+a² = 0