[Maths Class Notes] on Rhombus Formula Pdf for Exam

A rhombus is a quadrilateral in Euclidean plane geometry, whose four sides have the same length. Often, a rhombus is called a diamond. Each rhombus is simple and is a special case of a kite and a parallelogram. A square is a rhombus with right angles. In a way, all squares can be considered rhombuses but every rhombus is not necessarily a square. Here, the concepts and formulas of a rhombus, like the formula of the area of a rhombus, are discussed in detail.

Area of Rhombus Formula

When dealing with Rhombus, the first question a student gets is How to find the area of a rhombus? Since we have a different formula to find an area of the rhombus.

Let’s discuss all formula of the rhombus briefly:

1. Based on Side of the Rhombus Formula

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Area of rhombus when side and height is given

A = a * h

Where a = length of sides of the rhombus

h = height.

2. Based on Diagonal of Rhombus Formula

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Area of Rhombus when diagonal of rhombus formula is given:

[A = frac{1}{2} times d_{1} times d_{2}]

Where d₁ and d₂ are the diagonals of the rhombus, the formula of diagonal of the rhombus is given as follows:

[d_{1} = sqrt{4a^{2} – d_{2}^{2}}]

[d_{2} = sqrt{4a^{2} – d_{1}^{2}}]

3. Based on the Perimeter of the Rhombus Formula

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Rhombus area and perimeter formula are given: 

A= 2*a*r

Where a = length of sides of the rhombus

r = radius of a circle inscribed in the rhombus

P= perimeter of rhombus= 4*a

Semiperimeter= 2*a

4. Based on Height and Vertex Angle

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Area of Rhombus when height and vertex angle is given:

[A = frac{h^{2}}{sin alpha}]

Where h= height and α = vertex angle

Questions on the Area of Rhombus Formula:

1) Find the area of the rhombus when the side is 4 cm and the height is 6 cm.

Ans: Area of rhombus when side and height is given,

A = a * h

From question a = 4cm and h = 6cm. Substituting these values we get,

A = 4 * 6 = 24 cm2

2) The diagonals of the rhombus are given as 8 cm and 12 cm. Find the area of the rhombus.

Ans: Area of rhombus when diagonals are given,

[A = frac{1}{2} times d_{1} times d_{2}]

From question d1=8 cm and d2=12 cm. Substituting these values we get,

[A = frac{1}{2} times 8 times 12 = 48] cm2

Conclusion

The name “Rhombus” derives from the word “Rhombos” used in Ancient Greece. It means a piece of wood whirled to make a roaring noise on a string. We see rhombus-shaped figures every day today, in various spheres of life, hence it is very important to learn and understand the concepts of this shape.