Geometry Area of a Right Triangle
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How Big
Area of a Right Triangle

 

 How do you figure out the area of a triangle?

 Let's step back and talk about the area of a rectangle.
 Like maybe this one:
 

 

 
 The area of the rectangle is equal to the height times the width.
 

 Area = Height Width

 3 4 = 12

 
 This is easier to see if we divide the rectangle
 into squares one unit on a side.
 

 

 
 and count the squares.
 
 Well maybe you already knew that one.
 And maybe you're saying:
 "What's that got to do with triangles?"
 
 This ...
 
 What's the area of this right triangle?
 

 

 
 This is like taking half the rectangle we had before.
 

 

 
 The area of the triangle is equal to half 
 the area of the rectangle.
 
 The formula for the area of the rectangle is:
 

 Area = height width

 
 So the formula for the area of a right triangle is:
 

 

 
 We could also write this formula as:
 

 

 
 Example:
 What is the area of this right triangle?
 

 

 Solution:

 

 

   copyright 2005 Bruce Kirkpatrick

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