$\displaystyle \begin{array}{{>{\displaystyle}l}} Giả\ sử\ A( 0;y_{0}) \ thuộc\ y=\frac{4}{3} x+4\ \\ \rightarrow y_{0} =\frac{4}{3} .0+4\rightarrow y_{0} =4\ \\ \rightarrow A( 0;4) \ hay\ OA=|4|=4\\ Giả\ sử\ B( x_{0} ;0) \ thuộc\ y=\frac{4}{3} x+4\ \\ \rightarrow 0=\frac{4}{3} x_{0} +4\ \\ \rightarrow x_{0} =-3\ \\ \rightarrow B=( -3;0) \ hay\ OB=|-3|=3\ \\ SOAB=\frac{OA.OB}{2} =\frac{3.4}{2} =6 \end{array}$