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Warm Up 1. What is the perimeter of a square with side lengths of 15 in.? 2. What is the perimeter of a rectangle with length 16 cm and width 11 cm?. 60 in. 54 cm. Learn to estimate the area of irregular figures and to find the area of rectangles and parallelograms . Vocabulary. area.
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Warm Up 1. What is the perimeter of a square with side lengths of 15 in.? 2. What is the perimeter of a rectangle with length 16 cm and width 11 cm? 60 in. 54 cm
Learn to estimate the area of irregular figures and to find the area of rectangles and parallelograms. Vocabulary area
The area of a figure is the amount of surface it covers. We measure area in square units.
2 The area of the figure is about 30 mi . Additional Example 1: Estimating the Area of an Irregular Figure Find the area of the rectangle. Count full squares: 19 red squares. Count almost-full squares: 9 blue squares. Count squares that are about half-full: 4 green squares = 2 full squares. Do not count almost empty yellow squares. Add. 19 + 9 + 2 = 30
A =lw A = 15 •9 A = 135 The area is about 135 in2. Additional Example 2: Finding the Area of a Rectangle Find the area of the figure. Write the formula. 15 in. Substitute 15 for l. 9 in. Substitute 9 for w.
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.
A = bh 1 __ 1 1 Substitute 2 for b and 1 for h. __ __ A = 2 •1 2 2 4 1 __ 4 5 5 __ __ A = • 2 4 25 1 ___ __ A = or 3 8 8 1 __ The area is 3 ft2. 8 Additional Example 3: Finding the Area of a Parallelogram Find the area of the parallelogram. Write the formula. 1 1 ft 4 1 2 ft 2 Multiply.
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To find the area to be tiled, subtract the area of the island from the area of the floor. 221 – 18 = 203 The area of the kitchen to be tiled is 203 ft2. Additional Example 4: Recreation Application Jessika 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? – = floor area island kitchen area to be tiled Substitute for l and w in A = lw. – = (13 • 17) (3 • 6) n Use the order of operations.
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Lesson Quiz for Student Response Systems 1. Find the area of the figure. A. 53.9 m2B. 53.9 m2 C. 54.6 m2D. 54.9 m2
Lesson Quiz for Student Response Systems 2. Find the area of the figure. A. 60 ft2B. 70 ft2 C. 80 ft2D. 90 ft2
Lesson Quiz for Student Response Systems 3. Find the area of a parallelogram with base 19 ft and height 11 ft. A. 209 ft2B. 214 ft2 C. 216 ft2D. 220 ft2