(1) Please use an algebraic expression containing t to express the coordinates of point C and point P;
(2) A circle with a radius of 1/2 t (one-half t) with a center at point C intersects with the X axis at two points A and B (point A is on the left side of point B) to connect PA and Pb.
(1) When it has something in common with Ray De, find the value range of t;
② When △PAB is an isosceles triangle, find the value of t. 。
Supplement to the question: