The discussion clarifies that the equation cos + sin does not equal zero in a general sense, as both functions are independent and do not have fixed values. It explores specific instances where sin and cos can sum to zero, such as sin(2n pi) + cos[(pi/2) + n pi] = 0, but emphasizes that this is not universally applicable. The relationship cosx + sinx = 0 leads to cotx = -1, but sinx = 0 does not hold in this context. Additionally, the maximum and minimum values of sinx + cosx are discussed, confirming that the function is continuous and must cross zero at some point. The thread concludes by distinguishing this topic from general calculus questions.