\documentclass[tikz, border=5mm]{standalone}
\usepackage{tkz-euclide}
\usetikzlibrary{calc}

\begin{document}
	\begin{tikzpicture}[scale=1.2]
		% ===== 1. 绘制平面直角坐标系 =====
		\tkzInit[xmin=-0.5, xmax=5, ymin=-2.5, ymax=1.5]
		\tkzDrawXY[noticks, >=latex] 
		\tkzLabelX[orig, font=\small]
		\tkzLabelY[orig, font=\small]
		
		% 坐标轴标签
		\tkzText[below](4.8,0){\small $x$}
		\tkzText[left](0,1.2){\small $y$}
%		
%		% ===== 2. 绘制点P(1,1)和点A(0,-2) =====
%		\tkzDefPoint(1,1){P}
%		\tkzDefPoint(0,-2){A}
%		
%		% 标记点
%		\tkzLabelPoint[right](P){$P(1,1)$}
%		\tkzLabelPoint[left](A){$A(0,-2)$}
%		\tkzDrawPoints[fill=black, size=3](P,A)
%		
%		% ===== 3. 在x轴正半轴上找点B使PA=PB =====
%		% 计算PA距离
%		\tkzCalcLength(A,P)\tkzGetLength{PAlen}
%		
%		% 以P为圆心，PA为半径作圆
%		\tkzCompass[color=blue, line width=0.4pt](P,A)
%		
%		% 求圆与x轴的交点（会得到两个交点）
%		\tkzInterLC[with nodes, R](P,\PAlen pt)(0,0)(1,0)\tkzGetPoints{B1}{B2}
%		
%		% 选择x>0的点作为B（根据问题要求取正半轴上的点）
%		\tkzDefPointBy[projection=onto (0,0)--(1,0)](P)\tkzGetPoint{H}
%		\iftkzPointNearX{B1}{0}
%		\tkzDefPoint(0,0){temp}
%		\tkzDefMidPoint(B1,temp)
%		\iftkzDimSign{\tkzPointResult}
%		\tkzCopyPoint[from=B2, to=B]
%		\else
%		\tkzCopyPoint[from=B1, to=B]
%		\fi
%		\else
%		\tkzCopyPoint[from=B1, to=B]
%		\fi
%		
%		% ===== 4. 连接PA、PB =====
%		\tkzDrawSegment[blue, thick](P,A)
%		\tkzDrawSegment[red, thick](P,B)
%		
%		% 标记点B
%		\tkzDrawPoint[fill=red, size=3](B)
%		\tkzLabelPoint[above](B){$B$}
%		
%		% 添加距离标记
%		\tkzLabelSegment[above left, pos=0.6](P,A){$PA$}
%		\tkzLabelSegment[above right, pos=0.6](P,B){$PB$}
%		
%		% 添加几何关系说明
%		\tkzText[below, align=center, font=\small](2.5,-2.3){
%			几何条件：$PA = PB$ \\
%			点B坐标：$(\pgfmathparse{\tkzGetPointCoordinate{B}{x}\tkzGetPointCoordinate{B}{x}}\pgfmathresult, 0)$
%		}
	\end{tikzpicture}
\end{document}