March 12: How do we calculate the area of rectangles and triangles? (AIM)

Aim: How do we calculate the area of rectangles and triangles?

 

• Well for starters, the are of a rectangle is very different from the area of a triangle. 

• The area of a triangle has a formula like this:

Area would equal
1/2 times the base
and height.

• The area of a rectangle has a formula like this:

The length is multiplied
by the width.

• Sometimes in a question, you'll get a shape that looks kind of funny. But if you break it down, there might be a triangle or/and a rectangle. For example in this problem:

What would be the area
for this figure? 

• So you would break it down like this:

Let's break it down into two parts.
Part A is a rectangle,
& Part B is a triangle. 

• Part A is a square:

1. Area of A = w x h = (20m) × (20m) = 400m²

• Part B is a triangle: 

       Area of B = ½(b × h) or (b × h)/2 = ½ × (20m × 14m) = 140m²

• Now to find the area of that figure you saw earlier, you add the 2 areas:

       Area = (Area of A) + (Area of B) = 400m² + 140m² = 540m² 

 

                                                      Now you try it !

• What is the area of this triangle ?

1. 30
2. 90
3. 56
4. 28

Sources Cited:

1. http://www.math-worksheets.info/2010/06/worksheets-area-triangle/
2. http://ed101.bu.edu/StudentDoc/current/ED101fa09/arl2013/Area.html
3. http://www.mathsisfun.com/area.html
4. John Schnatterly AKA -->  http://johnschnatterly.blogspot.com/