x=-3y所袜早以设P(-3a,a)则√[(-3a)²+a²]=|-3a+3a-2|/圆扒√(1²+1²)平方10a²=4/2=2a=±√告腔雀5/5所以P(-3√5/5,√5/5),(3√5/5,-√5/5)