What is the length of the diagonal of a rectangle whose width is 90 cm and whose length is 200 cm?
The diagonal is
The diagonal of a rectangle makes a right triangle, with the diagonal (d) as the hypotenuse, and the length (l) and width (w) as the other two sides.
You can use the Pythagorean theorem to solve for the diagonal (hypotenuse).
Take the square root of both sides.