Perimeter and area

Perimeter and area

The perimeter of a shape is the distance around the outside of the figure. It is the length of the boundary of a two-dimensional figure. For a polygon we can find the perimeter by adding the individual lengths of its edges. Units of perimeter are the units of length. For example, mm, cm, m and km.
The area of a figure is the size of the region inside it. We use appropriate formulas to find the area of various shapes. Units of area are: mm², cm², m² and km².

Question 1

This shape is made from 5 small equilateral triangles and 1 large equilateral triangle.
What is the length of the outer perimeter of the shape?

Detailed description of diagram

Solution

Each small equilateral triangle has side length 5 cm. The large equilateral triangle has 3 small equilateral triangles along its base. Therefore each side of the large equilateral triangle has length 15 cm.

The perimeter of the whole shape	= 15 + 15 + 4 × 5
	= 50 cm.

Question 2