standard_description: Explain how the criteria for triangle congruence (ASA, SAS, and SSS) follow from the definition of congruence in terms of rigid motions.
problem_activity: Task
In triangle $\Delta ABC$, point $M$ is the point of intersection of the bisectors of angles $\angle BAC$, $\angle ABC$, and $\angle ACB$.  The measure of $\angle ABC$ is $42^\circ$, and the measure of $\angle BAC$ is $64^\circ$.  What is the measure of $\angle BMC$?
[IMG]
This task adapted from a problem published by the Russian Ministry of Education.


aligns: no