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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

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The perimeter of a figure is the distance around it. To find the perimeter you can add the lengths of the sides.

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Additional Example 1: Finding the Perimeter of a Polygon Find the perimeter of the figure. 2.8 + 3.6 + 3.5 + 3 + 4.3 Add all the side lengths. The perimeter is 17.2 in.

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Try This: Example 1 Find the perimeter of the figure. 3.3 + 3.3 + 4.2 + 4.2 + 3 Add all the side lengths. 3.3 in. 4.2 in. 3 in. The perimeter is 18 in.

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Additional Example 2: Using a Formula to Find Perimeter Find the perimeter P of the rectangle. P = 2l+ 2w Substitute 12 for l and 3 for w. P = (2 12) + (2 3) P = 24 + 6 P = 30 Multiply. Add. The perimeter is 30 cm. 12 cm 3 cm

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How many individual boxes are there here?

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1234567 2 3 4 5 6 7

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Learn to find the area of rectangles, triangles, and parallelograms.

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Vocabulary area Insert Lesson Title Here

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The area of a figure is the amount of surface it covers. We measure area in square units.

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Additional Example 2: Estimating the Area of a Rectangle Find the area of the figure. Write the formula. Substitute 15 for l. Substitute 9 for w. A = lw A = 15 9 A = 135 The area is 135 in 2. 15 in. 9 in.

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Try This: Example 2 Find the area of the figure. Write the formula. Substitute 13 for l. Substitute 7 for w. A = lw A = 13 7 A = 91 The area is 91 in 2. 13 in. 7 in.

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46 ft. 3 ft.

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46 ft. 3 ft.

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25 cm. 5 cm.

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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.

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Additional Example 3: Finding the Area of a Parallelogram Find the area of the parallelogram. Write the formula. Multiply. A = bh 2 ft 1 2 A = 2 1 1 2 __ 1 4 Substitute 2 for b and 1 for h. 1 2 __ 1 4 A = 5 2 __ 5 4 A = or 3 25 8 ___ 1 8 __ The area is 3 ft 2. 1 8 __ 1 4 1 ft

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Try This: Example 3 Find the area of the parallelogram. Write the formula. Multiply. A = bh A = 1 3 1 2 __ 1 2 Substitute 1 for b and 3 for h. 1 2 __ 1 2 A = 3 2 __ 7 2 A = or 5 21 4 ___ 1 4 __ The area is 5 ft 2. 1 4 __ 1 1 ft 2 1 3 ft 2

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I made a DELICIOUS peanut butter and jelly sandwich for lunch today. I’m so excited to eat it!!! Dylan came to me crying and said he forgot his lunch! Since I’m so nice, I cut my sandwich diagonally and gave one piece to Dylan and kept one for myself. Who got more of the sandwich??

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You can make a square out of two congruent triangles.

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If the area of a triangle is HALF the area of the rectangle, what could we use for the formula of a triangle?

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New Formula We can pretend the triangle is a rectangle and find the area of the rectangle! Then divide it by two. LW ÷ 2

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New Formula We can pretend the triangle is a rectangle and find the area of the rectangle! Then divide it by two.

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Additional Example 4: Finding the Area of a Triangle Find the area of the triangle. Write the formula. Substitute 9.6 for b. Substitute 2.9 for h. Multiply. The area is 13.92 cm 2.A = 13.92 A = bh 1 2 __ A = (9.6 2.9) 1 2 __ A = (27.84) 1 2 __

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Try This: Example 4 Find the area of the triangle. Write the formula. Substitute 8.5 for b. Substitute 3.4 for h. Multiply. The area is 14.45 cm 2. 3.4 cm 8.5 cm A = 14.45 A = bh 1 2 __ A = (8.5 3.4) 1 2 __ A = (28.9) 1 2 __

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Lesson Quiz Find the area of each figure. 1. 2. 3. What is the area of a parallelogram with base 16 in. and height 10 in.? 4. What is the area of a triangle with base 10 in. and height 7 in.? Insert Lesson Title Here 4.5 m 9.2 m 41.4 m 2 24 ft 2 160 in 2 35 in 2

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