Parallelogram Formula: Theorems and Formulas

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A parallelogram is a two-dimensional shape. It has four arms, of which two pairs of opposite arms are parallel. The opposite sides of a parallelogram are equal in length, and the opposite angles are equal in measure, while the sum of the adjacent angles of a parallelogram is equal to 180 degrees. A quadrilateral is a closed geometric shape with 4 vertices, 4 sides and so 4 angles that are located on the same plane. For a quadrilateral, the sum of the interior angles is 360 degrees. A quadrilateral is a type of polygon. There are different types of quadrangles embracing Trapezoids, parallelograms, and kites.

Key Takeaways: Parallelogram, quadrilateral, parallel, Area, Perimeter, dimensional, congruent, parallelepiped


What is Parallelogram?

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A parallelogram is a quadrilateral with two parallel and equal sides. A quadrilateral is called a parallelogram if two pairs of opposite sides of a quadrilateral are equal then it is a parallelogram. If two opposite sides of a quadrilateral are parallel and equal, then this quadrilateral is a parallelogram. If inside a quadrilateral, the corners bisect each other, then this quadrilateral is a parallelogram.


Theorem of Parallelogram

Following are the Theorems of Parallelogram:

Theorem 1: Parallelograms on the same base and between the same parallel sides are equal in area.

Theorem 2: The area of a parallelogram is the product of its base and the corresponding altitude.


What is Parallelogram Formula?

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A geometric shape with two opposite arms and opposite angles equal is defined as a parallelogram. If the image is two-dimensional, it is called parallelogram, and if the image is three-dimensional, it is called parallelepiped.

The formula for the area of a parallelogram is, Area = b × h

The formula for the perimeter of a parallelogram is, = 2 (a + b)

Where the base of a parallelogram is b and the height of that parallelogram is h and a is the side adjacent to the base.

Perimeter of a Parallelogram Formula

The circumference of a parallelogram is the total distance of the boundary of a parallelogram. To determine the circumference of a parallelogram, one needs to know its length and width. Let the arms of the parallelogram be a and b. Keeping in mind the characteristics of a parallelogram, that is, the opposite arms are parallel and consistent. The perimeter of a parallelogram is as given below:

  • Perimeter = a + b + c + d (when a, b, c, d are representing 4 sides of a parallelogram)
  • Since, side AB = CD = b, side BC = AD = a; Perimeter of a parallelogram = 2 (a + b)

Area of a Parallelogram Formula

The number of square units inside the polygon is the area of a parallelogram. The area of a parallelogram is the area or surface occupied by a two-dimensional plane. The area of a parallelogram can be determined by multiplying the base and the height. To find the area of a parallelogram, the base and height must be perpendicular.

Area of Parallelogram Formula Using Height and Base

Area of a Parallelogram Formula Without Height

  • In case of height of the parallelogram is not given, trigonometry can be used to find the area.
  • Area of parallelogram formula = a b sin (x) = b a sin (x)

Area of a Parallelogram Using Diagonals

Also, the area of any parallelogram can be calculated using its diagonal lengths of it. Let’s assume, the diagonals d1 and d2 intersect each other at an angle x, then the area of the parallelogram is given by: 

  • Area of parallelogram formula = ½ × d1 × d2sin (x)

Points to Remember

Following are some important points:

  • All parallelograms are quadrilaterals.
  • All quadrilaterals are not parallelograms.
  • All Squares and Rectangle will have the properties of parallelograms while all the parallelograms may not be squares or rectangles.
  • The only example of a regular quadrilateral is square. 
  • The volume of a parallelogram cannot be determined as a parallelogram is a two-dimensional shape.
  • Not all parallelograms and not all quadrilaterals are parallel.

Sample Questions

Ques: Find the area of a parallelogram with a base is 10 cm and a height is 5 cm. (2 Marks)

Ans: Given:

Base, b = 10 cm

Height, h = 5 cm

Area of parallelogram = b × h = 10 × 5 = 50 cm2

Therefore, the area of the parallelogram = 50 cm2

Ques: Find the perimeter of a parallelogram whose base is 20 cm and height is 12 cm. (2 Marks)

Ans: Given:

Base, b = 20 cm

Height, h = 12 cm

Perimeter of a parallelogram = 2(Base + Height) = 2(20 +12) = 2 × 32 = 64 cm

Therefore, the perimeter of the parallelogram = 64 cm

Ques: The height of a parallelogram is 15 inches and the base is 9 inches then find the perimeter of the parallelogram. (2 Marks)

Ans: Given:

Base, b = 9 inches

Height, h = 15 inches

Perimeter of a parallelogram = 2(Base + Height) = 2(9 +15) = 2 × 24 = 48 inch

Therefore, the perimeter of the parallelogram = 48 inch

Ques: Find the perimeter of a parallelogram whose height is 10 cm and the base is 8 cm. (2 Marks)

Ans: Given that:

Base, h = 10 cm

Height, b = 8 cm

From the formula, perimeter of a parallelogram = 2(Base + Height) = 2(10+8) = 36 cm

Hence, the perimeter of the parallelogram = 36 cm

Ques: Using the parallelogram formula, find the area of the parallelogram with the base of 6 cm and height of 8 cm. (2 Marks)

Ans: Given:

Base, b = 6 cm

Height, h = 8 cm

Using parallelogram formula, Area of Parallelogram = b × h = 6 × 8 = 48 cm2

Therefore, the area of the parallelogram = 48 cm2

Ques: What will be the area of a parallelogram if its base is 4 cm and height is 8 cm?(2 Marks)

Ans: Given:

Base, b = 4 cm

Height, h = 8 cm

Using parallelogram formula, Area of Parallelogram = b × h = 4 × 8 = 32 cm2

Therefore, the area of the parallelogram = 32 cm2

Ques: Find the perimeter of a parallelogram with side measures 5 m and 7 m using the parallelogram formula. (2 Marks)

Ans: Given:

a = 5 m

b = 7 m

We know that, Perimeter of a Parallelogram = 2( a + b) = 2(5 + 7) = 24 m

Hence, the perimeter of the parallelogram is 24 m

Ques: Find the perimeter of parallelogram if the height is 44 m and base is 36 m. (2 Marks)

Ans: Given:

h = 44 m

b = 36 m

We know that, Perimeter of a Parallelogram = 2( b + h) = 2(36 + 44) = 2 × 80 = 160 m

Hence, the perimeter of the parallelogram is 160 m

Ques: Find the perimeter of parallelogram if the height is 50 cm and base is 40 cm. (2 Marks)

Ans: Given:

h = 50 cm

b = 40 cm

We know that, Perimeter of a Parallelogram = 2( b + h) = 2(50 + 40) = 2 × 90 = 180 cm

Hence, the perimeter of the parallelogram is 180 cm.

Ques: Determine the area of a parallelogram whose height is 3 cm and the base is 5 cm. (2 Marks)

Ans: Given that, the base of the parallelogram (b) = 5 cm and Height of the parallelogram (h) = 3 cm

We know that the formula for Area of Parallelogram = b × h 

= 5 × 3 = 15 cm2

Therefore, the area of the parallelogram = 15 cm2

Ques: Determine the perimeter of a quadrilateral whose sides measure 5 cm, 4 cm, 5 cm, and 4 cm taken in order. (1 Mark)

Ans: The perimeter of a quadrilateral is the sum of all 4 sides of the quadrilateral. Hence, Perimeter of a quadrilateral = 5 + 4 + 5 + 4 = 18 cm.

Ques: Calculate the area and perimeter of a parallelogram whose base length, adjacent side, and height are 5 cm, 4 cm, and 11 cm respectively.(2 Marks)

Ans: The given parameters are:

Base length, b = 5 cm

Adjacent side, a = 4 cm

Height, h = 11 cm

The equation for area of a parallelogram is: Area = b × h = 5 × 11 = 55 cm2

Perimeter of a parallelogram is given by:

Perimeter = 2(a + b) = 2(4 + 5) = 2 × 19 = 18 cm

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    Two water taps together can fill a tank in $8\frac{8}{9}$ hours. The tap of larger diameter takes 4 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.


      • 2.
        PQ and PR are two tangents to a circle with centre O and radius 5 cm. AB is another tangent to the circle at C which lies on OP. If OP = 13 cm, then find the length AB and PA.


          • 3.
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