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VTMO 2026 - Grade 7 - Final - SET 2 - Self-study Question 3

VTMO · VTMO 2026 - Grade 7 - Final - SET 2 - Self-study

Question 3

Triangle $ABC$ is right-angled at $A$. The ray $Bx$ is the internal bisector of $\angle A$ [the source angle label is preserved]. From $C$, draw the perpendicular to $Bx$, meeting it at $D$. Let $M$ be the midpoint of $AC$, and let $DM$ meet $BC$ at $N$.

a) Prove that triangle $DAC$ is isosceles.

b) Prove that $N$ is the midpoint of $BC$.

c) Given $BD=AC$, find $\angle ABC$.