# Rhombus sides and diagonals relationship

### rhombuses_masson_buckelew The diagonals of a rhombus bisect each other at right angles. Page Navigation: Definition of rhombus Characterizations of rhombus Basic properties of rhombus Side of rhombus Diagonals of rhombus Perimeter of rhombus. The rhombus is a parallelogram with four congruent sides. A square is a formula 3: area = (1/2)*d1*d2, where d1 and d2 are the lengths of the two diagonals.

The centre of this rotation symmetry is the circumcentre O described above, because the vertices are equidistant from it. Other triangles do not have reflection or rotation symmetry In a non-trivial rotation symmetry, one side of a triangle is mapped to a second side, and the second side mapped to the third side, so the triangle must be equilateral. In a reflection symmetry, two sides are swapped, so the triangle must be isosceles. Thus a triangle that is not isosceles has neither reflection nor rotation symmetry.

Such a triangle is called scalene. Rotation symmetry of a parallelogram Since the diagonals of a parallelogram bisect each other, a parallelogram has rotation symmetry of order 2 about the intersection of its diagonals.

This is even clearer in a rectangle than in a general parallelogram because the diagonals have equal length, so their intersection is the circumcentre of the circumcircle passing through all four vertices.

## Rhombus: Properties and Shape

The line through the midpoints of two opposite sides of a rectangle dissects the rectangle into two rectangles that are congruent to each other, and are in fact reflections of each other in the constructed line. There are two such lines in a rectangle, so a rectangle has two axes of symmetry meeting right angles. It may seem obvious to the eye that the intersection of these two axes of symmetry is the circumcentre of the rectangle, which is intersection of the two diagonals.

This is illustrated in the diagram to the right, but it needs to be proven.

• Rhombus. Formulas, characterizations and properties of rhombus
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• Rhombus Problems

An equilateral triangle has three axes of symmetry, which are concurrent in the circumcentre of the circumcircle through its three vertices. It also has rotation symmetry of order three about its circumcentre.

A triangle that is not isosceles has no axes of symmetry and no rotation symmetry. A parallelogram has rotation symmetry of order two about the intersection of its diagonals. A rectangle has rotation symmetry of order two about the intersection of its diagonals, and two axes of symmetry through the midpoints of opposite sides.

Definition of a rhombus A rhombus is a quadrilateral with all sides equal.

## What is the perimeter of a rhombus whose diagonals are 16 and 30?

Construction of a square and a rhombus using GSP and the definition of a square and a rhombus. Click here to open a GSP sketch. You will find a segment that is 9. Click here to see the final square. You will find another segment that is 9. Construct a "Kite" shaped rhombus, with segment AB as one side.

The mathematical definition of a circle is all the points that are equal distance from the center point. Use circles with equal radii to construct a rhombus. Click here to see the final rhombus. Explain why the quadrilateral ABCD is a rhombus. The way we constructed the rhombus implies that all the lengths are equal. Each of the sides of the rhombus are all radii of circles that were created with equal radii. Exloring the Diagonals of a Rhombus.

### Rhombus. Formulas, characterizations and properties of rhombus

Lengths of the diagonals of a rhombus vs. Click here to open a square in GSP and measure the diagonals. What relationship did you find between the two diagonals of a square? They have equal lengths. Use what you know about squares to explain why the diagonals must be equal for a square? Since a square is a special type of a rhombus, should the diagonals of rhombuses be equal? Are the lengths of the two diagonals the same length for a rhombus? After you measured the lengths of the diagonals, you would discover that they are not equal.

Midpoint of the diagonals of a rhombus. Now, using the same rhombus, mark the center point E, where the diagonals intersect.