Compare how you draw the resultant vector in each method. Look at the initial point and the ending point.
See solution.
Practice makes perfect
Let's consider two vectors a and b.
To add the vectors using the parallelogram method, translate b so that its tail touches the tail of a. Next, we complete the parallelogram. The resultant is the diagonal of the parallelogram that starts at the tail of the vectors.
To use the triangle method, we translate b so that its tail touches the tip of a. The resultant is the vector from the tail of a to the tip of b.
In both methods, the resultant starts at the same point. However, in the parallelogram method, the ending point of the resultant is the opposite vertex of the parallelogram formed, while in the triangle method, the ending point is the tip of the second vector.
