FINDING AREA AND PERIMTER OF REGULAR POLYGONS

What is polygon ?

A polygon can be defined as a flat or plane, two-dimensional closed shape with straight sides. It does not have curved sides.

Regular polygon :

A polygon having equal sides and equal angles is a regular polygon.

To find area of regular polygon, we use the formula

What is Apothem ?

A line from the center of a regular polygon at right angles to any of its sides.

Find the perimeter area of each regular polygon. Leave your answer in simplest form.

Example 1 :

Name of the shape = pentagon, length of apothem = 7.3 cm and side length = 10.6 cm

Solution :

A pentagon is any polygon that has five sides and five angles.

Number of sides = 5

Perimeter of pentagon = 5 x 10.6

= 53 cm

Perimeter = 53 cm

Length of apothem = 7.3 cm

Example 2 :

Name of the shape = triangle, length of apothem = 14 cm and side length = 28√3 cm

Solution :

Number of sides of triangle = 3

length of apothem = 14 cm and

side length = 28√3 cm

Perimeter = 3(28√3)

= 84√3 cm

Example 3 :

Name of the shape = 7-gon, length of apothem = 21.8 cm and side length = 21 cm

Solution :

Number of sides = 7

length of apothem = 21.8 cm and

side length = 21 cm

Perimeter = 7(21)

= 147 cm

Example 4 :

Name of the shape = octagon, length of apothem = 14.1 cm and side length = 11.7 cm

Solution :

Number of sides = 10

length of apothem = 14.1 cm and

side length = 11.7 cm

Perimeter = 8(11.7)

= 93.6 cm

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