Lesson 11.1 Areas of Parallelograms

Objectives Find perimeters and areas of parallelograms. Determine whether points on a coordinate plane define a parallelogram.

Areas of Parallelograms A parallelogram is quadrilateral with both pairs of opposite sides ll. Any side of the parallelogram can be called a base. There is a corresponding altitude that is perpendicular to each base.

If a parallelogram has an area of a square units, a base of b units, and a height of h units, then A = bh Key Concept

Example 1:Find the Perimeter and Area of  ACEG AC = 28 Ft. AG = 15 Ft. Use to find the height of parallelogram  ACEG. To find the area substitute for A=bh. The perimeter of  ACEG = 86 feet Area= about 297

Example 2: Use area to solve a real-world problem. RECREATION Blue Sky Water Park is having a new pool designed for their visitors. Find the total surface area of the water in the pool. To find the total surface area of the water, divide the pool into rectangles. Then find the area of each rectangle and add the areas to find the total area. Rectangle 1:w = 15 m, l = 20 m Rectangle 2:w = or 15 m, l= 25 m Rectangle 3:w = 10 m, l = or 10 m Rectangle 1 A= l w = 20  15 = 300 m 2 Rectangle 2 A =lw = 25  15 = 375 m 2 Rectangle 3 A= l w = 10  10 = 100 m 2 The total area is 775 m.

Example 3: Area on a Coordinate Plane COORDINATE GEOMETRY The vertices of a quadrilateral are Q(-1, 4), R(2, 1),S(-1, -2), and T(-4, 1).

Assignment Page – 19, 20 – 28 evens