Answer:
The two triangles are related by hypotenuse leg
so the triangles are congruent
======================================================
Explanation:
The square markers indicate we have 90 degree angles. This means the two triangles are right triangles.
The tickmarks tell us which sides correspond and are the same length. The double tickmarked sides are the hypotenuses of each triangle. They are the same length because of the matching tickmarks. The same can be said about the legs marked with single tickmarks.
Based on those tickmarks, and the fact we have right triangles, we can use the hypotenuse leg theorem to prove the triangles are congruent.
The hypotenuse leg theorem only works for right triangles.
Since "hypotenuse leg" is used quite often in geometry, it is abbreviated to "HL".