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10.1 Area of Rectangles and Parallelograms I can find the area of rectangles and parallelograms Area Rap Warm Up 1. What is the perimeter of a square with side 60 in. lengths of 15 in.? 2. What is the perimeter of a rectangle with length 16 cm and width 11 cm? 54 cm The area of a figure is the amount of surface it covers. We measure area in square units. Find the area of the figure. 15 in. A = lw 9 in. The area is about 135 in2. Find the area of the figure. 13 in. A = lw 7 in. The area is about 91 in2. You can use the formula for the area of a rectangle to write a formula for the area of a parallelogram. Imagine cutting off the triangle drawn in the parallelogram and sliding it to the right to form a rectangle. The area of a parallelogram = bh. The area of a rectangle = lw. The base of the parallelogram is the length of the rectangle. The height of the parallelogram is the width of the rectangle. Find the area of the parallelogram. A = bh 1 1 ft 4 2 1 ft 2 25 1 ___ __ A= or 3 8 8 1 2 __ The area is 3 ft . 8 Find the area of the parallelogram. 3 1 ft 2 A = bh 1 1 ft 2 21 1 A = ___ or 5 __ 4 4 1 2 __ The area is 5 4 ft . Jessica is going to tile a kitchen that measures 13 ft by 17 ft. Some floor space is taken up by an island that measures 3 ft by 6 ft. How much area remains to be tiled in the kitchen? The area of the kitchen to be tiled is 203 ft2. Miguel is going to landscape his backyard that measures 16 ft by 11 ft. Some of the backyard space is taken up by a built-in BBQ that measures 2 ft by 4 ft. How much area remains to be landscaped? The area of the backyard to be landscaped is 168 ft2. Lesson Quiz Find the area of each figure. 1. 2. 41.4 m2 48 ft2 3. What is the area of a parallelogram with base 16 160 in2 in. and height 10 in.? 4. A square fish pond that is 6 ft long is surrounded by a square walk that is 18 ft long. What is the area covered by the walk? 288 ft2 10.2 Area of Triangle and Trapezoids I can find the area of triangles and trapezoid You can divide any parallelogram into two congruent triangles. So the area of each triangle is half the area of the parallelogram. Find the area of the triangle. A = 1 bh 2 A = 120 The area is 120 ft2. Find the area of the triangle. A = 1 bh 2 A = 360 The area is 360 in2. 12 cm Find the area of the trapezoid. 7 cm A = 1 h(b1 + b2) 2 A = 98 The area is 98 cm2. 16 cm Lesson Quiz Find the area of each triangle. 1. 39.9 cm2 2. Find the area of each trapezoid. 3. 4. 22.5 m2 84 mi2 113 3 2 in 4