prove concylic (maths) 15pts

1.有咩方法可以證4點係concylic,請詳細列出方法(最好中英解釋)

(如果不懂答第2題,可只答第1條)

2.P(3t,3/t) and R(-3/t,-3t)are two distinct points on the hyperbola H:xy=9, where t not equal -1,0 and 1. The tangents to H at P and R intersect at the point Q while the normals to H at P and R intersect at the point S.

Prove PQRS are concylic. 請列出不同的方法.