哈雷慧星绕太阳运动的轨道是一个椭圆。它离太阳最近距离为<img src="https://nimg.ppkao.com/2019-05/wuacheng/2019051617123324083.jpg?sign=c3de517b64c15585203eaa01f7bc4b14&t=62d67511" />时的速率是<img src="https://nimg.ppkao.com/2019-05/wuacheng/2019051617125638101.jpg?sign=5aef76117a65b248446e565433980859&t=62d67511" />它离太阳最远时的速率是<img src="https://nimg.ppkao.com/2019-05/wuacheng/2019051617131120557.jpg?sign=ce79f47546011da3c8e88159e30ac513&t=62d67511" />这时它离太阳的距离r₂是多少？