How to Find the Perimeter of a Triangle

 

Title: How to Find the Perimeter of a Triangle

Introduction:-

Triangles are one of the fundamental shapes in geometry. Understanding their properties and being able to calculate their various attributes is essential for both students and professionals and teachers in various fields. One of the most basic calculations for a triangle is finding its perimeter, which is the sum of the lengths of all its sides. In this article, I will try to explain into the various methods of How To Find The Perimeter Of A Triangle, including different types of triangles and the different cases to consider.

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Explanation:-

Understanding the Basics
Before I start this topic,How To Find The Perimeter Of A Triangle, let's establish a few key concepts and definitions:

Triangle Types: 

Based on sides triangles are divided in three categories:
(a)Equilateral Triangle: A triangle whose all three sides are equal is called equilateral triangle.

In the picture,
ABC is an equilateral triangle,whose
AB = BC = AC
(b)Isosceles Triangle: A triangle whose any two sides are equal and third one is different is called isosceles triangle.

In the picture,
PQR is an isosceles triangle whose
  PQ = PR
(c)Scalene Triangle: A triangle whose all three sides are different to one another is called a scalene triangle.

In the picture,
 XYZ is a scalene triangle whose,
  XY ≠ YZ ≠ ZX

Sides and Vertices:

(i)The sides of a triangle are the line segments that form the boundaries of the triangle.
(ii)The vertices of a triangle are the points where the sides meet.

Perimeter:

The perimeter of a triangle is the total length or sum of all its sides.

Sides of a Triangle:

In an equilateral triangle, all sides have the same length, which we'll denote as 'a.'
In an isosceles triangle, two sides have the same length, and the third side is 'b.'
In a scalene triangle, all three sides have different lengths, which we'll denote as 'a,' 'b,' and 'c.'
With these basic concepts in mind, let's discuss  How To Find The Perimeter Of A Triangle in various scenarios.

Procedure 1:

 Perimeter of an Equilateral Triangle:
An equilateral triangle is a special case where all sides are of equal length. To find its perimeter, we  will simply multiply the length of one side ('a') by 3, as there are three equal sides.
So,Perimeter of an Equilateral Triangle (P) = 3a

Some problems related on equilateral triangle:-

(a) The measure of each side of an equilateral triangle is 5 cm, Find its perimeter.

Solution:-

∵ Each side of the equilateral triangle(a) = 5cm
∴ Perimeter of the equilateral triangle = 3a
= (3 × 5)cm
= 15 cm
(b) The perimeter of an equilateral triangle is 21cm, find its each side.

Solution:-

 ∵The perimeter of equilateral triangle = 21 cm
∴ Its each side measure = 21/3 
                                       = 7cm

Procedure 2: 

Perimeter of an Isosceles Triangle:

An isosceles triangle has two sides of equal length ('a') and one side of different length ('b'). To calculate its perimeter, we will add the lengths of the two equal sides ('a') and the different side ('b').
So,
Perimeter of an Isosceles Triangle 
(P) = 2a + b

Some problems related on isosceles triangle:

(a) The measure of two equal sides of an isosceles triangle is 7m each and third side is 5m, find the perimeter of the isosceles triangle.

Solution:-

∵ The measure of each equal side of the isosceles triangle(a) = 7m
The measure of third side (b) = 5m
∴ Perimeter of the isosceles triangle = 2a + b
= (2 × 7 + 5)m
= (14 + 5)m
= 19 m
(b)The perimeter of an isosceles triangle is 27m,the measure of its third side is 3m, find the measure of its each equal side.

Solution:-   1st Method:

∵ Perimeter of isosceles triangle = 27m
Measure of its third side(b) = 3m
Let, measure of each equal side = a meter
 A/Q,
  2a + b = 27
=> 2 × a + 3 = 27
=> 2 × a = 27 - 3
=> 2 × a  = 24
=> a = 24/2
=> a = 12
∴ Measure of each equal side of the isosceles triangle (a) = 12 m

2nd Method:

    ∵ Perimeter of isosceles triangle = 27m
Measure of its third side(b) = 3m
∴Measure of each equal side(a) = (Perimeter - b) / 2
= (27 -3)/2
= 24/2
= 12 m

(c)The perimeter of an isosceles triangle is 20 cm, its equal sides measure 4cm, Find its third side.

Solution:- 1st Method:

The perimeter of an isosceles triangle = 20cm
Measure of its equal sides (a) = 4cm
Let, measure of its third side = b cm
A/Q,
    2a + b = 20
  => 2 × 4 + b = 20
 => 8 + b = 20
 => b = 20 - 8
 => b = 12
∴ Measure of third side(b) = 12 cm

2nd Method:

   The perimeter of an isosceles triangle = 20cm
Measure of its equal sides (a) = 4cm
∴ Measure of its third side (b) =   perimeter - 2a
  = (20 - 2 × 4)
 = 20 - 8
 = 12 cm

Procedure 3: 

Perimeter of a Scalene Triangle:

In a scalene triangle, all three sides have different lengths ('a,' 'b,' and 'c'). To find the perimeter, we will simply add the lengths of all three sides.
∴Perimeter of a Scalene Triangle 
(P) = a + b + c

Some Problems on scalene triangle:

(a) Three sides of a scalene triangle are 3m, 4m, and 5m respectively, Find the perimeter of the triangle.

Solution:-

   ∵ 1st side (a) = 3m
     2nd side (b) = 4m
and 3rd side (c) =5m
∴ Perimeter of scalene triangle (P) = (3 + 4 + 5) = 12 m

(b)Perimeter of a scalene triangle 15 cm, its two sides are 6cm and 7cm; find third side.

Solution:-  1st Method:

Perimeter of a scalene triangle (P) = 15 cm
 1st side (a) = 6 cm
 2nd side (b) =7 cm
∴ Third side (c)= P - (a + b)
                       = 15 - (6+7)
                       =15 - 13
                      = 2 cm

2nd Method:

Perimeter of a scalene triangle (P) = 15 cm
 1st side (a) = 6 cm
 2nd side (b) =7 cm
Let,the third side = c cm
A/Q,
    a + b + c = P
 => 6 + 7 + c = 15
=> 13 + c = 15
=> c = 15 - 13
=> c = 2
∴ Third side (c) = 2 cm

(c)The perimeter of a scalene triangle is 30m and sum of its two side is 20m,find the third side.

Solution:-

∵ Perimeter of scalene triangle = 30m
Sum of its two sides = 20m
∴ Measure of third side = Perimeter - Sum of its two sides
= (30 - 20)m
= 10m

Let us, experiment this above formula of finding perimeter of scalene triangle with a calculator.

Scalene Triangle Perimeter Calculator:-

Side A:

Side B:

Side C:

Perimeter:

Procedure 4: 

Using the Pythagorean Theorem:

As we all know thatThe Pythagorean Theorem is an important and fundamental principle in geometry that relates the sides of a right triangle. In a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides. This theorem can also be used to find the perimeter of a right triangle.
Let us suppose, we have a right triangle with sides 'a' and 'b' and a hypotenuse 'c.' To find the perimeter, we would add the lengths of all three sides:
Perimeter of a Right Triangle 
P = a + b + c
This method is especially useful when dealing with right triangles, but it can also be applied to other types of triangles.

Procedure 5: 

Semi-Perimeter and Heron's Formula:

Heron's Formula is a powerful tool for finding the area of a triangle, and it can be used to find the perimeter as well. Heron's Formula depends on the semi-perimeter of the triangle, which is half of the perimeter. First, we will calculate the semi-perimeter, and then we will use it to find the perimeter.
Semi-Perimeter of a Triangle (S):
S = (a + b + c) / 2
Once we have the semi-perimeter, we can use Heron's Formula to find the area of the triangle:
Area of a Triangle (A):
A = √(S × (S - a) × (S - b) × (S - c))
Finally, to find the perimeter, we will double the semi-perimeter.
Perimeter of a Triangle (P)= 2S

Procedure 6: 

Using Trigonometry:

If we know the angles and at least one side length, we can use trigonometric functions to find the other sides and then calculate the perimeter. The most commonly used trigonometric functions for this purpose are the sine, cosine, and tangent.
For example, In a right triangle if we have an angle 'A' and the side 'a,' and we want to find the side 'b,' we can use the sine function:
Sine Rule:
sin(A) = (b / a)
Solving for 'b,' we will get:
b = a × sin(A)
We will repeat this process for the other sides, 'b' and 'c,' using their corresponding angles 'B' and 'C.'
Once we have all three side lengths, we can find the perimeter using the formula mentioned earlier for a scalene triangle:
Perimeter of a Scalene Triangle (P) = a + b + c

Procedure 7: 

Coordinate Geometry:

In some cases, we may be given the coordinates of the vertices of a triangle on a coordinate plane. To find the perimeter, we can use the distance formula to calculate the lengths of the sides.
Suppose we have the coordinates of the vertices A(x₁, y₁), B(x₂, y₂), and C(x₃,y₃). we can use the distance formula to find the lengths of sides 'a,' 'b,' and 'c':

Distance Formula:
Length of side (a) = √((x₂ - x₁)² + (y₂ - y₁)²)
Length of side (b) = √((x₃ - x₂)² + (y₃ - y₂)²)
Length of side (c) = √((x₁ - x₃)² + (y₁ - y₃)²)
Once we have the side lengths, wecan find the perimeter as usual:
Perimeter of a Triangle (P)= a + b + c

Real-Life Applications:

Understanding How To Find The Perimeter Of A Triangle is not just an academic exercise. It has numerous practical applications in everyday life and various fields, including:

1.Construction: Builders and architects always use knowledge of perimeter to determine the amount of material needed for projects involving triangles, such as roofing, flooring, or fencing.

2.Engineering: In structural engineering, finding the perimeter is crucial for designing load-bearing structures, bridges, and other architectural marvels.

3.Landscaping: Landscape designers often use perimeter calculations to plan garden beds, walkways, and other outdoor features.

4.Navigation: In navigation and geolocation, the perimeter of a triangle always help determine distances between points on the Earth's surface.

5.Art and Design: Artists and designers use triangular shapes in various projects. Understanding perimeter.

Conclusion:-

How To Find The Perimeter Of A Triangle is a fundamental concept in geometry and trigonometry. Depending on the type of triangle and the given information, we can use various methods to calculate the perimeter. For scalene, isosceles, and right triangles, we simply add up the side lengths. In the case of an equilateral triangle, we multiply the length of one side by 3 to find the perimeter. When we are given angles rather than side lengths, the Law of Sines and the Law of Cosines become invaluable tools for determining the perimeter.
By understanding these methods and applying them to different triangle scenarios, every one will be better equipped to work with triangles in various mathematical and real-world applications. Whether anyone is solving geometry problems, measuring physical objects, or designing structures, the ability to find the perimeter of a triangle is a valuable skill that serves as a building block for more advanced mathematical..........

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FREQUENTLY ASKED QUESTIONs on Perimeter of a Triangle:-

How do you find the perimeter of a triangle in Class 7?

Answer:- As we know three sides of an equilateral triangle are equal. ∴The perimeter of an equilateral triangle = 3 × a [Where, a is measure of each equal side] An isosceles triangle has two sides equal. ∴Perimeter of an isosceles triangle = 2a + b [ Where, a = Measure of each equal side and b = Measure of unequal third side] A scalene triangle has three different sides. ∴ Perimeter of a scalene triangle = a +b + c where, a,b and c are its three different sides.

Is triangle 180 degrees?

Answer:- Sum of three angles of any triangle is = 180°, if sum of all three angle grater than 180°, then it will not form a triangle.

What is a unique triangle?

Answer:- If the sum of any two sides is greater than third side and sum of all angles of a triangle is 180°,then it is a unique triangle.

What is a formula of trapezium?

Answer:- The formula of perimeter of a trapezium = Sum of all its four sides. Again, Area of a trapezium = ½ (a+b) × h where, a and b are its parallel sides and h is the perpendicular distance between parallel sides.

What is a formula of a rectangle?

Answer:- Perimeter of a rectangle = 2(l + b), where, l = length of the rectangle and b = breadth of the rectangle Area of the rectangle = l × b where, l = length of the rectangle and b = breadth of the rectangle

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