The axis passing through PD∨y intersects AB at point C and X at point D. Because the straight line is Y=x and the angle DCO= 45, then the angle dco = the angle ecp = 45, that is, △EPC is an isosceles right angle, ∴PE=EC= 1, and the Pythagorean theorem is PC=

The abscissa of ∵P is 2, so the abscissa of point C is 2, and △ODC is an isosceles right angle △, so CD=OD=2.

So the ordinate of p is PD=PC+CD= radical number 2+2.

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