Happy New Year from MrBillDoesMath!
Answer:
Proof by ASA congruence postulate. See below
Discussion:
Fact 1 : angle A = angle T (given)
Fact 2: The angles on both sides of point X are equal as vertical angles
are equal.
From these facts it follows that angle M = angle H (as all plane triangles have 180 degrees). Also AM = TH (given) so
In the left triangle In the right triangle
(angle M, side AM, angle A) = (angle H, side TH, angle T)
Hence the triangles have two congruent angles, and congruent sides included between the angles, so they are congruent by ASA.
Thank you,
MrB