[tex]\it \Delta ABE-\ dreptunghic\ \^{i}n\ B,\ cu\ ipotenuza\ AE-\ diametrul\ cercului[/tex]
[tex]\it \left.\begin{aligned}\widehat{BEA}=\dfrac{\stackrel\frown{AB}}{2}\\ \\ \\ \widehat{BCA}=\dfrac{\stackrel\frown{AB}}{2}\end{aligned}\right\} \Rightarrow \widehat{BEA}= \widehat{BCA}\ \Rightarrow\ \widehat{BEA}= \widehat{PCA}\ \ \ \ \ (1)[/tex]
[tex]\it Din\ \Delta ABE, dreptunghic\ \^{i}n\ B \Rightarrow \widehat{BAE}=90^o- \widehat{BEA}\ \ \ \ \ \ (2)[/tex]
[tex]\it Din\ \Delta APC, dreptunghic\ \^{i}n\ P \Rightarrow \widehat{PAC}=90^o- \widehat{PCA}\ \stackrel{(1)}{=}\ 90^o-\widehat{BEA}\ \ \ \ \ (3)[/tex]
[tex]\it (2).\ (3) \Rightarrow\widehat{BAE}=\widehat{PAC}\ \Rightarrow\ \widehat{BAE}\ \equiv\ \widehat{PAC}[/tex]
