Finding the Perimeter of Geometric Figures

Types of parallelograms

Types of parallelograms
Perimeter of a square
Perimeter of a square

What do we need to know about the square? A square has four equal sides!

Formula: P = a + a + a + a
or
P = 4.a

The task from the example:
P = 4.2
P = 16 sm

Perimeter of a rectangle
Perimeter of a rectangle

What do we need to know about the rectangle? A rectangle consists of two opposite equal sides!

Formula: P = a + a + b + b
or
P = 2.a + 2.b

The task from the example:
P = 2.4 + 2.2
P = 12 sm

Types of triangles

Types of triangles
Perimeter of an equilateral triangle
Perimeter of an equilateral triangle

What should we know about this kind of triangle triangle? An equilateral triangle has three equal sides!

Formula: P = a + a + a
or
P = 3.a

The task from the example:
P = 3.2
P = 6 sm

Perimeter of an isosceles triangle
Perimeter of an isosceles triangle

What should we know about this kind of triangle triangle? An isosceles triangle has two equal sides!

Formula: P = a + b + b
or
P = a + 2.b

The task from the example:
P = 2 + 2.3
P = 8 sm

Perimeter of a scalene triangle
Perimeter of a scalene triangle

What should we know about this kind of triangle triangle? Scalene triangle has no equal sides!

Formula:
P = a + b + c

The task from the example:
P = 2 + 3 + 4
P = 9 sm