Math Lesson

AREA OF TRIANGLE

The area of a polygon is the number of square units inside the polygon. Area is 2-dimensional like a carpet or an area rug.
A parallelogram is a 4-sided shape formed by two pairs of parallel lines. Opposite sides are equal in length and opposite angles are equal in measure. To find the area of a parallelogram, multiply the base by the height. The formula is:
where is the base, is the height, and · means multiply.
The base and height of a parallelogram must be perpendicular. However, the lateral sides of a parallelogram are not perpendicular to the base. Thus, a dotted line is drawn to represent the height. Let's look at some examples involving the area of a parallelogram.
Example 1:	Find the area of a parallelogram with a base of 12 centimeters and a height of 5 centimeters.
Solution:
	= (12 cm) · (5 cm)
	= 60 cm2
Example 2:	Find the area of a parallelogram with a base of 7 inches and a height of 10 inches.
Solution:
	= (7 in) · (10 in)
	= 70 in2
Example 3:	The area of a parallelogram is 24 square centimeters and the base is 4 centimeters. Find the height.
Solution:
	24 cm2 = (4 cm) ·
	24 cm2 ÷ (4 cm) =
	= 6 cm
Summary:	Given the base and height of a parallelogram, we can find the area. Given the area of a parallelogram and either the base or the height, we can find the missing dimension. The formula for area of a parallelogram is:
	where is the base, is the height, and · means multiply. http://www.mathgoodies.com/lessons/vol1/area_triangle.html