1. Area of Triangles

2. The area of a triangle is ½ the area of a rectangle.
A = ½ x length x width
A = ½ lw
A = lw/2
To find the area of a triangle, you can multiply the length and width then divide by 2.
OR…You can solve ½ x length x width.

3. LENGTH is the same a BASE. WIDTH is the same as HEIGHT. See below…
WIDTH HEIGHT
LENGTH BASE

4. LENGTH is the same a BASE. WIDTH is the same as HEIGHT. See below…
WIDTH HEIGHT
LENGTH BASE
A TRIANGLE’S BASE IS TYPICALLY THE BOTTOM PART OF A TRIANGLE WHILE THE HEIGHT IS ALWAYS THE STARTS AT THE HIGHEST POINT FROM THE BASE, STRAIGHT DOWN. THE TWO LINES ALWAYS CREATE A RIGHT ANGLE.

5. So, area of a triangle is ½ x base x height.
A = ½ bh or bh/2

6. Sometimes the base line and the height line are not clearly identified because the given triangle is not a right triangle. When this is the case, identify any line as a base and draw and imaginary height line. The imaginary height line, also called the altitude, creates a right angle with the base line.

7. This visual shows HOW a triangle has an area ½ of that of the rectangle, with the same base and height.

8. Here is another example…
Area of the rectangle = 18 units The triangle = 9 units2