To find the length of the diagonal, we will use the pythagoras theorem
opposite² + adjacent² = hypotenuse²
let x be the length of the diagonal, which is equal to the hypotenuse
opposite = 16
adjacent = 5
substitute the values into the formula;
16² + 5² = x²
256 + 25 = x²
281 = x²
Take the square root of both-side of the equation
16.76 = x
Thee length