Square root of 5

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The square root of 5 is the positive real number that, when multiplied by itself, gives the prime number 5. This number appears in the fractional expression for the golden ratio. It can be denoted in surd form as: sqrt{5}. , Geometrically, the square root of 5 corresponds to the diagonal of a rectangle whose sides are of length 1 and 2, as is evident from the Pythagorean theorem. Such a rectangle can be obtained by halving a square, or by placing two equal squares side by side. Together with the algebraic relationship between ¿5 and ¿, this forms the basis for the geometrical construction of a golden rectangle from a square, and for the construction of a regular pentagon given its side (since the side-to-diagonal ratio in a regular pentagon is ¿).