Area of a Deltoid (Kite)

🏆Practice deltoid area

How do we calculate the area of a kite?

The area of the kite can be calculated by multiplying the lengths of the diagonals and dividing this product by 2 2 .

Deltoid Area Formula

To facilitate the understanding of the concept of calculus, you can use the following drawing and the accompanying formula:

A=KM×NL2A=\frac{ KM\times NL}{2}

1 - Area of a deltoid

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Test yourself on deltoid area!


ACBD is a deltoid.



Given in cm:

AB = 6

CD = 10

Calculate the area of the deltoid.


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There are many geometric shapes that can be found during the solving of engineering problems at all different stages of study, such as in high school, in matriculation exams, and even in psychometry. One of the less trivial shapes is the deltoid and, as part of the questions surrounding it, students are often asked to calculate the area of the deltoid.

What is the deltoid?

A deltoid is a polygon with four sides (that is, a quadrilateral) with two distinct sets of adjacent sides of equal length to each other.

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Types of Deltoids

There is a clear distinction between convex deltoid and concave deltoid.

Convex deltoid

Convex deltoid is a deltoid where the diagonals are inside and cross each other. The longer diagonal acts as a main diagonal, while the shorter diagonal acts as a secondary diagonal.

As you can observe in the following drawing, the main diagonal divides the deltoid into two overlapping triangles, that is, identical, and the secondary diagonal divides the deltoid into two isosceles triangles whose bases are adjacent and, indeed, identical. 

Do you know what the answer is?

Concave Kite

Concave kite is a kite where one of the diagonals (main diagonal) passes inside the kite and the other diagonal (secondary diagonal) passes outside the kite.

The concave deltoid can be described as a shape consisting of two isosceles triangles that share a common base, where one triangle contains the other triangle. The following drawing better describes the concave deltoid:

  • When all sides of the kite have the same length, a rhombus is obtained, which is actually a special case of a kite.
  • Another special case of a kite is a square, when it is a case where all sides and all angles are of the same size. 

Properties of the Kite

  • The angles on the sides, or more precisely, the angles between the different adjacent sides of the kite, are of equal size.
  • The diagonals of the kite are perpendicular to each other 
  • The main diagonal in the convex kite (or its extension in the concave kite) crosses the secondary diagonal (in both cases), and therefore actually functions as a perpendicular bisector
  • The main diagonal equally divides (crosses) the main angles of the kite
  • Every convex kite has the possibility of enclosing a circle
  • In every kite, there are two sets of adjacent sides of equal size
  • As mentioned, a concave kite is characterized by a secondary diagonal located outside of it

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Practice on the Area of a Kite

Exercise 1

The area of the kite must be calculated according to the attached drawing and the existing data:

  • BK=3cm BK= 3 cm
  • AC=7cmAC= 7 cm
The area of the kite must be calculated according to the attached drawing and the existing data


According to the kite area formula, we are missing the length of the diagonal BDBD.

We know that the diagonal BKBK is equal to 33 cm, and according to one of the properties of the kite, the diagonal ACAC divides the diagonal BDBD into two equal parts.

That is, from this we can conclude that BD=6BD=6.

A=(AC×BD)2=(7×6)2=21 A=\frac{(AC\times BD)}{2}=\frac{(7\times6)}{2}=21

At this point, we can place the data in the area formula and obtain:


The area of the kite ABCDABCD is 2121 cm².

Exercise 2

Given the kite KLMNKLMN whose area is 144144 cm², the meeting point of the diagonals LNLN and KMKM.

The area of the section KP must be calculated according to the attached drawing and the existing data:

  • LN=18LN=18 cm
  • A=144A=144 cm²
4 - Given the kite KLMN


This exercise is a reverse calculation, that is, we know the area and we are asked to calculate the length of the segment KPKP.

In the first step, we replace the data we know in the kite area formula.

We obtain:

A=(LN×KM) A=(LN\times KM)

144=(18×KM)2 144=\frac{(18\times KM)}{2}

We simplify the expression and obtain:

288=18×KM 288=18\times KM

KM=16 KM=16

In fact, we found the length of the second diagonal of the kite.

According to one of the properties of the kite, the diagonal LNLN divides the diagonal KPKP into two equal parts.

From here we obtain that KPKP is equal to 88 cm.


KP=8 KP=8 cm

Examples and exercises with solutions for the Area of the Kite


Given kite ABCD AB=BC DC=AD

The diagonals of the kite intersect at point 0

Given BD=14 The area of the kite is 42 cm²

Calculate the side AO



We replace the data we have in the formula for the area of the kite:

Diagonal by diagonal divided by 2, we replace the existing data in the formula:

S=AC×BD2 S=\frac{AC\times BD}{2}

42=AC×142 42=\frac{AC\times14}{2}

We multiply by 2 to get rid of the denominator:

 14AC=84 14AC=84

We divide by 14:

AC=6 AC=6

Let's pay attention that we were asked about AO.

It is known that in a rhombus, the main diagonal crosses the second diagonal, therefore:

AO=AC2=62=3 AO=\frac{AC}{2}=\frac{6}{2}=3


3 cm

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