NCERT Example - Rectangle diagonals - Quadrilaterals
Question: A carpenter has one wooden strip of length 8 cm to use as a diagonal of a rectangle. What must be true about the other strip (diagonal), and where should the two strips be joined?
Answer: Other diagonal also 8 cm; join both strips at their midpoints. Perpendicular strips give a square.
Full step-by-step NCERT solution with diagrams on Something by Zero.