Geometry: Perimeter of a Polygon
This is a free lesson from our course in Geometry
 
   
In this lesson you’ll learn about the concepts of Perimeter of Polygons, and how to find the perimeter there of. The presentation covering such content will be done by the instructor in own handwriting, using video and with the help of several examples with solution. This will help you understand and master the formulas of important geometry applications in this area, and how to apply them to find solution.
Perimeter of Polygons: is the measurement of the distance around the outside of the polygon i.e. the perimeter of a polygon is the sum of the lengths of all its sides. E.g. in the figure below; you can see an irregular hexagon (A, B, C, D, E, F), whose perimeter is:
(4 cm + 4cm + 4cm +4cm + 5cm + 5cm) = 26 cm.
Irregular Hexagon
(More text below video...)
<h2> Geometry - Perimeter of a Polygon</h2> <p> perimeter, polygon, video, formula, sum, geometry, length, side, perimeter of a polygon, quadrilateral, pentagon, rectangle, opposite, congruent, radius, geometry tutorials, solution, practice questions, quizzes</p> <p> The perimeter of a pentagon ABCDE with each side measuring 3cm is 15cm.</p>
Other useful lessons:
Circumference of a Circle
Effect of dimension changes on perimeter
Real World Applications
(Continued from above) In case of ‘Regular Polygon’; meaning whose sides are equal and also all the angles are equal, perimeter can be determined by “length of the side x number of sides”. For example, perimeter of a Pentagon (5 sides polygon), is 5 times length of side and in case of Heptagon (7 sides polygon), the perimeter is 7 times length of side.
Perimeter of Polygons: Summary
 
Figure Polygon Perimeter/Circumference
 
Square 4a
Rectangle 2l + 2w or 2(l + w)
Parallelogram 2a + 2b or 2(a + b)
Triangle (a + b + c)
Trapezoid (a + b1 + c + b2)
Regular Polygon ns
n =  number of sides
Circle * d or 2 * * r
You can explore now how the concepts can be applied to solve the problems using relationship and properties of polygons. For example:
Given: a regular hexagon in inscribed in a circle of radius 10 cm. You are to find out the perimeter of this hexagon.
As learnt earlier, hexagon is six sides polygon. Draw a diagram a below:
Perimeter and Circumference-Regular Polygon
AOP is found out by,
AOP = 360 / 6 = 60 (it is six sided regular polygon)
• As OA = OP = 10 cm,  OAP is isosceles, and thus OAP = OPA
Therefore, all three angles of the triangle are equal and it is an equilateral triangle. Hence
AP = OA = OP = 10 cm.
As it is a six sided polygon, thus perimeter of the polygon is 6*10 = 60 cm, as the final answer.
The video above will explain more in detail about Perimeter of Polygons, with the help of several examples.
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