Final answer:
The length of side RS in parallelogram QRST can be determined by knowing the length of the opposite side QT since they are equal in a parallelogram. Without specific values, you cannot give a definitive length, but the method would involve standard geometric or vector principles.
Step-by-step explanation:
To answer the question regarding the length of side RS in parallelogram QRST, we must look at the properties of parallelograms. In a parallelogram, opposite sides are equal in length. Therefore, to determine the length of side RS, you would simply need to find the length of the opposite side, which is side QT in this case. If the length of side QT is provided or can be calculated through some means (like using coordinates, vectors, or additional information about diagonals and angles), then this length would be the same as the length of side RS in parallelogram QRST.
From the provided information, it appears reference is being made to either vector addition or subtraction using a parallelogram, but without specific values for the sides, a definitive length cannot be given. To measure the length RS, you would use the same method used to find any side on a parallelogram, including using the Pythagorean theorem if the parallelogram is right-angled at one of the vertices or using trigonometry and vector principles in more complex scenarios.