Let’s take a triangle ABC

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Perimeter of ∆ABC = Sum of all sides

= AB + BC + AC

 

What about specific triangles?

 

Perimeter of Isosceles triangle

In an Isosceles triangle,

  Two sides are equal

Perimeter of triangle - Part 2

Here,

  AB = AC = a

  BC = b

 

So,

   Perimeter ∆ABC = Sum of all sides

= AB + BC + AC

= a + b + a

= 2a + b

 

Perimeter of Equilateral triangle

In an Equilateral triangle,

  all sides are eqaul

Perimeter of triangle - Part 3

Here,

  AB = AC = BC = a

 

So,

   Perimeter ∆ABC = Sum of all sides

= AB + BC + AC

= a + a + a

= 3a

 

Let’s take some examples

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 4

Perimeter of ∆ABC = Sum of all sides

= AB + BC + CA

= 3 + 5 + 4

= 12 cm

 

∴ Required perimeter is 12 cm

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 5

Perimeter of ∆ABC = AB + BC + CA

= 15 + 24 + 12

= 51 cm

∴ Required perimeter is 51 cm

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 6

Perimeter of ∆ABC = Sum of all sides

        = AB + BC + AC

        = 12 + 17 + 10

        = 39 cm

 

∴ Required perimeter is 39 cm

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 7

Here,

  AB = AC = 8cm

  BC = 4 cm

 

    Perimeter of ∆ABC = Sum of all sides

    = AB + BC + AC

    = 8 + 4 + 8

    = 20 cm

 

∴ Required perimeter is 20 cm

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 8

Since all sides are equal,

it is an equilateral triangle

Here, AB = BC = CA = a = 5cm

 

Perimeter of equilateral ∆ABC = 3a

  = 3 (5)

  = 15 cm

 

∴ Required perimeter is 15 cm

 

Find perimeter of Δ ABC

Perimeter of triangle - Part 9

Since all sides are equal,

it is an equilateral triangle

Here, AB = BC = CA = a = 9 cm

 

Perimeter of equilateral ∆ABC = 3a

= 3 (9)

= 27 cm

 

∴ Required perimeter is 27 cm

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.