Question

Let BD bisect 2ABC. If m_ABD =(3x+8) and m DBC =(7x+4), then what is the measure of ABD?

Answer 1

$\begin{gathered} m\angle ABD=m\angle\text{DBC} \\ 3x+8=7x+4 \\ 3x-7x=4-8 \\ -4x=-4 \\ x=\frac{-4}{-4} \\ x=1 \\ m\angle ABD=3x+8 \\ m\angle ABD=3(1)+8 \\ \angle ABD=11\text{ degree} \end{gathered}$

Note a bisector divide an angle into 2 equal half.