tan(α+8π/7)=tan(π+α+π/7)=tan(α+π/7),即：tan(α+π/7)=asin（22π/7+α）+3cos（α-20π/7）/ sin（20π/7-α）-cos（α+22π/7）=(sin(3π+π/7+α)+3cos(3π-2π/7-α))/(sin(3π-2π/7-α)-cos(3π+π/7...