Prove the sum of the squares of the lengths of a parallelogram’s diagonals is equal to the sum of the squares of the lengths of the sides.

u2-t3-s2-d3

Interactive

Sum of diagonal squares equals sum of side squares

demo

In a parallelogram, |d₁|² + |d₂|² equals the sum of the side squares. Drag and step the vector expansion.

Open fullscreen →

Request an applet

Describe the interactive you’d like — same inbox as applet feedback, tagged as a request for this syllabus id.