WXYZ is a parallelogram and it is a cyclic quadrilateral.

Activity 5c

Points R,S, and T are collinear or T is not a point on the circle centered at R with the radius RS.

Activity 5d

Some triangle are not equilateral . there is a triangle that is not equilateral. The negation of all, there exists at least one that is not.

Activity 5e

Given a line L and a point P that is not on L, either there is no line through P that is parallel to l or there are multiple lines through P that are parallel to L.