



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 
