Rectangle is a four sided shape with straight sides, interior angles of 90 degrees and what’s important for this question : opposite sides with equal length.
In the ABCD rectangle, opposite sides are AD and BC, which means their length is the same AD=BC and AC and BD , AB=CD. The diagonals all have same length in a rectangle. This means that the length of the diagonal BD is the same as the length of the diagonal AC, and BD=26cm. (Solution A)
