VTMO 2026 - Grade 9 - Semifinal - SET 1 - Self-study Question 18

Question 18

In triangle ABC, AD bisects $\angle A$, with $D\in BC$, and $\angle ADB:\angle ADC=4:5$. The perpendicular bisector of BC meets the line AD at M. Find $\angle ABM$.

Question illustration

$80^\circ$
$100^\circ$
$120^\circ$
$90^\circ$
$60^\circ$