Rectangle ‒ Circumscribed Circle

The rectangle is a parallelogram all of whose interior angles have size of 90 degrees ‒ the right angle. Opposite sides of the rectangle are always the same size. The square is a special case of a rectangle having sides all of the same length.

Each rectangle has two diagonals, which are the lines that connect non-adjacent peaks. In this figure it is the line segments AC and BD, figured also marked u₁ and u₂. These diagonals are always the same size. They are also always longer than either side of the rectangle. Unlike a square, the diagonals do not meet each other in a right angle. One diagonal divide the rectangle into two halves. The two diagonals then divide the rectangle into four quarters. The diagonals bisect each other. If we mark the middle point of the rectangle as S (as shown), then the length of the segment AS will be the same as the length of the segment CS.

The perimeter is the lengths of all the edges of the rectangle combined, thus the sum of the lengths of all four sides: a + b + a + b. However, since always two opposite sides are equal in length, the perimeter can be calculated as 2a + 2b.

The area of the rectangle is the size of surface, which the rectangle occupies. We calculate it by multiplying the length of one side by length of the other, neighboring side. True so that the area of the rectangle is equal to a · b.



**Mathematical formula**:



Perimeter:

O = 2a + 2b



Surface:

S = ab



Diagonal:

u₁ = a√a² + b²



The radius of the circle circumscribed:

rₒ = ½u₁