[tex]f:R-\ \textgreater \ R, f(x)=2x+4 \\ \\
Gf\ intersectat \ cu \ Ox = A(x_0;0) =\ \textgreater \ f(x)=0 \\
f(x) = 0 =\ \textgreater \ 2x+4=0 =\ \textgreater \ 2x=-4 =\ \textgreater \ x=-2 =\ \textgreater \ A(-2; 0) \\ \\
Gf \ intersectat \ cu \ Oy=B(0; y_0) =\ \textgreater \ f(0)=y_0\\
f(0)=2*0+4=4 =\ \textgreater \ B(0,4) \\ \\
AO=|-2|=2 \ (unitati) \\
BO=|+4| =4 \ (unitati) \\
AOB, m(A)=90^{o} =\ \textgreater \ AB^{2} = AO^{2}+BO^{2}=2^{2}+4^{2}=\ \textgreater \ AB= \sqrt{18}= 3\sqrt{2} \ (unitati) \ [/tex]
