Given the triangle ABC.
Angle A is a right angle which equals 90 degree.
And sum of angles in a triangle equals 180 degree.
[tex]\begin{gathered} A+B+C=180^0 \\ 90^0+B+C=180^0 \\ B+C=180^0-90^0 \\ B+C=90^0 \end{gathered}[/tex]
So, the possible measurement of B and C must be the ones who's sum is 90 degree.
[tex]\begin{gathered} 40\text{ \& 50 }\rightarrow40+50=90 \\ 30\text{ \& 60}\rightarrow30+60=90 \\ 45\text{ \& 45}\rightarrow45+45=90 \\ 80\text{ \& 30}\rightarrow80+30=110 \\ 60\text{ \& 40}\rightarrow60+40=100 \end{gathered}[/tex]
Therefore, the ones whose sum equals 90 degree are the answers;
[tex]\begin{gathered} 40\text{ \& 50} \\ 30\text{ \& 60} \\ 45\text{ \& 45} \end{gathered}[/tex]
