1. You have that:
 -Each blade on a windmill is in the shape of a triangle.
 - The triangle has the following dimensions: the base is 7 feet and the height is 4 feet.
 - There are four blazer on the windmill.
 2. Then, to solve this problem, you must apply the formula for calculate the area of a triangle, which is:
 A=bxh/2
 b is the base of the triangle (b=7 feet)
 h is the height of the trianlge (h=4 feet)
 3. Therefore, you have:
 A=bxh/2
 A=(7 feet)(4 feet)/2
 A=28 feet²/2
 A=14 feet²
 4. The total area is:
 At=Ax4
 At=(14 feet²)(4)
 At=56 feet²Â