Let’s take a triangle ABC
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
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
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 ∆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 ∆ABC = AB + BC + CA
= 15 + 24 + 12
= 51 cm
∴ Required perimeter is 51 cm
Find perimeter of Δ ABC
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
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
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
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