Final answer:
The question seems to involve representing signals with unit triangles and rectangles, but the provided information focuses on wave functions, vector addition, and trigonometry related to physics.
Step-by-step explanation:
The question is about representing signals as combinations of unit triangles (delta function, Δ(t)) and unit rectangles (rect(t)). However, the information provided seems to relate to the superposition of waves, vector addition, and trigonometric identities that one would encounter in a physics context, particularly with regard to wave functions, signal propagation, and vector operations. Specifically, the question mentions wave functions y1(x, t) and y2(x, t), vector addition with horizontal and vertical components, and the resultant wave equation utilizing trigonometric identities.
To answer the question regarding signals, you would need additional context about the specific forms of the signals in question. Nonetheless, the given information suggests that the subject of superposition and vector addition is being explored, where the resultant wave or vector is determined by algebraic and trigonometric methods.