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As shown in the figure, in the plane rectangular coordinate system, the straight line L is parallel to the X-axis and intersects with the Y-axis at point A, the point B in the first quadrant is on L, connecting OB, the moving point P satisfies the angle APQ=90 degrees, and PQ intersects with the X-axis at point C. 。
(1) When the moving point P coincides with point B, if the coordinate of point B is (2, 1), find the length of PA.
(2) When the moving point P is on the extension line of line segment OB, if the ordinate of point A is equal to the abscissa of point B, find the value of PA:PC.