Component-wise Analysis
3. Diving into Coordinates
Another way to determine if two vectors are parallel and, if necessary, adjust them, involves looking at their individual components. A vector in a 2D space has two components (x, y), while a vector in 3D space has three components (x, y, z). If two vectors are parallel, the ratio of their corresponding components will be the same.
For example, let’s say we have two vectors in 2D space: a = (a1, a2) and b = (b1, b2). For a and b to be parallel, the following must hold true: a1/b1 = a2/b2. If these ratios are equal, it means that one vector is simply a scaled version of the other, and hence they are parallel. If the ratios are not equal, you might consider adjusting the vectors to make them parallel (if that’s your goal).
Suppose you’re working with vectors p = (3, 6) and q = (1, 4). The ratios would be 3/1 = 3 and 6/4 = 1.5. Since 3 1.5, these vectors are not parallel. Now, if you want to make p parallel to q, you could scale q. To do this, you might say, “Okay, I want the x-component of q to be 3 (same as p).” To achieve this, you’d multiply q by 3, resulting in (3, 12). Now, q’ (which is 3q) = (3, 12) and p = (3, 6) are still not parallel. Because the second number in both vector’s are not parallel.
So, we need to be smart about it! In this scenario, the easiest thing to do might be to scale p. We could divide the second vector by 2. So, p’ (which is (1/2)p) = (1.5, 3) . Now the first number of vectors q = (1, 4) and p’ = (1.5, 3) are still not parallel. So, let’s just be honest here, and just adjust q = (3,6) so they will become parallel. q needs to be (3,6). Easy fix! This will be parallel if p = (3,6) and q=(3,6) are equal.