Sunday, November 18, 2012

Formulas for area

What is area?
Area is the size of a particular surface. And each shape has a special formula to calculate it's own area. I know a lot of people struggle with formulas and trying to remember what formula belongs to what shape. So I wanted to make a post that clearly states the name of the simple shape and provides the formula and a visual. I looked on many websites for a picture that would provide all of that information. I found one I really like from mathisfun.com. I originally thought about typing it all out and trying to find a picture to match my examples but this turned out to be much easier and I think a lot clearer. So bellow is the picture I found that clearly states the name of the shape, shows you it, and provides the formula for area.

Triangle
Area = ½ × b × h
b = base
h = vertical height
Square
Area = a2
a = length of side
Rectangle
Area = w × h
w = width
h = height
Parallelogram
Area = b × h
b = base
h = vertical height
Trapezoid (US)
Trapezium (UK)
Area = ½(a+b) × h
h = vertical height
Circle
Area = π × r2
Circumference = 2 × π × r
r = radius
Ellipse
Area = πab
Sector
Area = ½ × r2 × θ
r = radius
θ = angle in radians


I know we have gone over a few in class, but for me (and I hope I am not alone) sometimes when we learn them in class it feels scattered and we hear about them at different times. Which is fine for a lot of people. But I am one of those people that likes to see it all together and visually be able to compare them. It just makes it easier for me to remember them.

Here is a link to the website that provided the photo above.

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