# Deduce that the diagonals of a rhombus meet at right angles

### geometry - Why do rhombus diagonals intersect at right angles? - Mathematics Stack Exchange Prove: If a quadrilateral is a rhombus, then the diagonals are perpendicular bisectors of each other. Consider properties of parallel lines and vertical angles. Mar 6, have to work through square roots if you use the properties of the vector dot product and the parallelogram law to construct the rhombus. deduce that the diagonals of a rhombus--a parallelogram whose sides are all equal--meet at right angles. (hint: you may find it convenient to use SSS, which.

### Proof: Rhombus diagonals are perpendicular bisectors (video) | Khan Academy

M will also be M are congruent, we can define their measures with the same variable, x. So we have Therefore, we know that? M are both right angles. Our final illustration is shown below. Let's work on a couple of exercises to practice using the side and angle properties of parallelograms. After examining the diagram, we realize that it will be easier to solve for x first because y is used in the same expression as x in?

## Proof: Rhombus diagonals are perpendicular bisectors

Rbut x is by itself at segment QR. Since opposite sides of parallelograms are congruent, we have can set the quantities equal to each other and solve for x: Now that we've determined that the value of x is 7, we can use this to plug into the expression given in?

In order to solve this problem, we will need to use the fact that consecutive angles of parallelograms are supplementary. The only angle we can figure out initially is the one at vertex Y because all it requires is the addition of angles. We have Knowing that?

Y has a measure of will allow us to solve for x and y since they are both found in angles consecutive to? Let's solve for y first. We have All that is left for solve for is x now. We will use the same method we used when solving for y: The sides and angles of parallelograms aren't their only unique characteristics. Let's learn some more defining properties of parallelograms. Diagonals When we refer to the diagonals of a parallelogram, we are talking about lines that can be drawn from vertices that are not connected by line segments.

Every parallelogram will have only two diagonals. An illustration of a parallelogram's diagonals is shown below. We have two important properties that involve the diagonals of parallelograms.

## Properties of Parallelograms

Segments AE and CE are congruent to each other because the diagonals meet at point E, which bisects them. Segments BE and DE are also congruent. The two diagonals split the parallelogram up into congruent triangles. Let's use these properties for solve the following exercises. We know that the diagonals of parallelograms bisect each other. This means that the point E splits up each bisector into two equivalent segments.

Proof: Rhombus diagonals are perpendicular bisectors (Hindi) - Class 8 (India) - Khan Academy

Let's try to solve for x first. We are given that? We can deduce that? If we look at? HIJ, we notice that two of its angles are congruent, so it is an isosceles triangle. HIJ has a measure of 9x since? They meet at a point which is the centre of a circle through all three vertices. The point is called the circumcentre and the circle is called the circumcircle of the triangle. An equilateral triangle is also congruent to itself in two other orientations: 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. 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.

### Properties of Parallelograms | Wyzant Resources

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. 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.