Final answer:
Reflecting a triangle across two intersecting lines results in an isometry known as rotation, which is a transformation where the object is turned around a fixed point.
Step-by-step explanation:
When a triangle is reflected across two intersecting lines, this composition of reflections results in a specific type of isometry known as a rotation. Geometric optics principles such as the law of reflection, though related to angles and symmetries as well, are not directly relevant in solving this problem. Instead, by the rules of transformations in geometry, reflecting an object across two intersecting lines is equivalent to rotating the object around the point of intersection of the two lines by twice the angle between them.