in this problem we have that
Triangle JTN is an isosceels triangle, because the triangle has two equal sides and two equal interior angles
segment TE is the altitude of triangle JTN, its a perpendicular bisector segment JN
that means
JE=NE
we have
JT=NT
mso
triangle TJE and triangle TNE are congruent by SAS
triangles TJE and trTNE are acute triangles