In geometry, straightedge-and-compass construction – also known as ruler-and-compass construction, Euclidean construction, or classical construction – is the construction of lengths, angles, and other

In mathematics, a square root of a number x is a number y such that y 2 = x ; in other words, a number y whose square is x. For example, 4 and −4 are square roots of 16 because 4 2 = 2 = 16.