Elementary Geometry

Basic Geometry Formulas Logo


  • Side of a square: \(a\)
    Diagonal of a square: \(d\)
    Radius of the circumscribed circle: \(R\)
    Radius of the inscribed circle: \(r\)
    Perimeter: \(P\)
    Area: \(S\)
    1. A square is a regular quadrilateral. It has four equal sides and four equal angles (\(90^\circ\) angles).
    2. Square
    3. Diagonal of a square
      \(d = a\sqrt 2\)
    4. Radius of the circumscribed circle
      \(R = d/2 =\) \(a\sqrt 2/2\)
    5. Radius of the inscribed circle
      \(r = a/2\)
    6. Perimeter of a square
      \(P = 4a\)
    7. Area of a square
      \(S = {a^2} = {\large\frac{{{d^2}}}{2}\normalsize} =\) \( 2{R^2} = 4{r^2}\)