Work out diagonal of a rectangle instantly with clear inputs, formula shown and shareable results.
A rectangle's diagonal closes a right triangle on its length and width, so Pythagoras gives d = √(l² + w²). The diagonal's angle to the long side is arctan(w/l).
Diagonal
d = √(l² + w²)
Diagonal angle
θ = arctan(w / l)
√(64 + 36) = 10 exactly — the 6-8-10 Pythagorean triple.
Yes. A television's stated size is its screen diagonal, so the same formula converts between diagonal and width/height.