to fin the last angle we have
the sum of all angles of a triangle is 180
then we sum the angles and match to 180
[tex]31+31+x=180[/tex]simplify
[tex]62+x=180[/tex]and solve for x
[tex]\begin{gathered} x=180-62 \\ x=118 \end{gathered}[/tex]we nee the value of the middle
because the point indicated for the angle is only half of this
now
[tex]\frac{118}{2}=59[/tex]the missing angle is 59°
