Areas of Polygons and Circles

Today I am going to be talking about what the area of a polygon is and how to find it. I need you to play close attention to the definitions and formulas that I will be providing you with! Never forget that MATH IS FUN!

"The area of a Polygon is the amount of space or region occupied by that polygon."

There are 2 methods to find areas other than the formulas and they can both be found on a geoboard or a dot paper. I will be showing you a video with one of the methods which I consider to be the clearest one which will be perfect for your future classroom.

 

when finding the area or perimeter or any type of calculation it is important not to forget the square units and how to convert them. Remember this sentence in order to remember how to convert in metric:  King      Henry     Died        Ugh     Drinking   Chocolate    Milk
             K:kilo   H:hecto-   D:deka-  U:unit  D:deci-     C:centi-       M:milli

 

Unit Name	Unit Symbol	Metric Equivalent	Imperial Equivalent
Metric...
square centimetre	cm²	1 cm² = 100 mm²	1 cm² = 0.1550 in²
square metre	m²	1 m² = 10,000 cm²	1 m² = 1.1960 yd²
hectare	ha	1 ha = 10,000 m²	1 ha = 2.4711 acres
square kilometre	km²	1 km² = 100 ha	1 km² = 0.3861 mile²
Imperial...	Unit Symbol	Imperial Equivalent	Metric Equivalent
square inch	in²		1 in² = 6.4516 cm²
square foot	ft²	1 ft² = 144 in²	1 ft² = 0.0929 m²
square yard	yd²	1 yd² = 9 ft²	1 yd² = 0.8361 m²
acre	acre	1 acre = 4840 yd²	1 acre = 4046.9 m²
square mile	mile²	1 mile² = 640 acres	1 mile² = 2.59 km²

 

Now I will provide you with the formulas needed to find the area of polygons!

Area of a square = s²

Area of a rectangle = lw    (length x width)    

Area of a triangle = bh   (1/2 x base x height) 

Area of a parallelogram = bh  (base x height) 

Area of a trapezoid = () or  1/2 x h   (b1: base 1 b2: base 2)

 

 

Lets find the area of the shape above:

1. First lets start with the rectangle laid horizontally. We know that the formula to find the area of a rectangle is A: lw  (length x width)

 

2. The length of a rectangle is the longest line, in this case the length of the rectangle is 6.5m. The width is the shortest line so the width of the first rectangle is 4m.

 

3) Now lets put it into play!   A: 6.5m x 4m = 26m^2

 

4) Lets do the same for the rectangle laid vertically!  A: 9m x 3.5m = 31.5m^2

 

5) GREAT JOB!! don't forget about changing the metric units to meter squared!

 

Area of a circle

 

area = π * (radius)²
π = 3.14

 

A: πr²

 

This is all for The Area of Polygons and Cirlces! I hope you enjoyed and I hope you are able to clear your doubts! If you need more information go to www.mathisfun.com and try how to find the areas of different shapes!