由x^2/a^2-y^2/b^2=1可得（x/a+y/b）（x/a－y/b）＝1所以x/a－y/b＝1/t,再结合x/a+y/b，可求得x=(t+1/t)a/2, y=(t-1/t)b/2
x^2/a^2-y^2/b^2=1,x^2/a^2-y^2/b^2=(x/a+y/b)(x/a-y/b)x/a+y/b=tx/a-y/b=1/tx=a(t+1/t)/2y=b(t-1/t)/2
