1. Copyright Tim Morris/St Stephen's School
Area of a Triangle
This is one in a series of Powerpoint slideshows to illustrate how to calculate the area of various 2-D shapes.
Start with the Rectangle, then move onto the Parallelogram.
After that select any of Triangle, Trapezium and Circle.
Please feel free to copy and modify any of these slide shows, but make sure you acknowledge the author when doing so.
Copyright Tim Morris/St Stephen's School

2. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
Copyright Tim Morris/St Stephen's School

3. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
COPY THIS!
Copyright Tim Morris/St Stephen's School

4. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
PASTE HERE!
Copyright Tim Morris/St Stephen's School

5. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
FLIP VERTICALLY!
Copyright Tim Morris/St Stephen's School

6. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
FLIP HORIZONTALLY!
Copyright Tim Morris/St Stephen's School

7. Copyright Tim Morris/St Stephen's School
TRIANGLE
L=length
H=height
What is the area of this triangle?
W=width
TRANSLATE TO HERE!
Copyright Tim Morris/St Stephen's School

8. Copyright Tim Morris/St Stephen's School
TRIANGLE
The area of the triangle is ½ the area of this parallelogram?
L=length
H=height
W=width
Copyright Tim Morris/St Stephen's School

9. Area = ½ (Width x Height) (perpendicular height H)
TRIANGLE
H=height
Area = ½ (Width x Height) (perpendicular height H)
W=width
Copyright Tim Morris/St Stephen's School

10. Area = ½ (Width x Height) (perpendicular height H)
TRIANGLE
H=height
Area = ½ (Width x Height) (perpendicular height H)
W=width
Copyright Tim Morris/St Stephen's School