# 10-4 Comparing Perimeter and Area Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day.

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10-4 Comparing Perimeter and Area Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day

Warm Up 1. What is the area of a figure made up of a rectangle with length 12 cm and height 4 cm and a parallelogram with length 12 cm and height 6 cm? 2. What is the area of a figure consisting of a triangle sitting on top of a rectangle? The triangle has a base of 12 in. and height of 9 in., and the rectangle has a base of 12 in. and height of 5 in. Course 1 10-4 Comparing Perimeter and Area 120 cm 2 114 in 2

Problem of the Day If sixteen people sit, evenly spaced, in a circle for story time, who sits directly across from person 5? person 13 Course 1 10-4 Comparing Perimeter and Area

Learn to make a model to explore how area and perimeter are affected by changes in the dimensions of a figure. Course 1 10-4 Comparing Perimeter and Area

Additional Example 1: Changing Dimensions Find how the perimeter and the area of the figure change when its dimensions change. Course 1 10-4 Comparing Perimeter and Area The original figure is a 4  2 in. rectangle. The smaller figure is a 2  1 in. rectangle. Draw a model of the two figures on graph paper. Label the dimensions. = 1 inch

Additional Example 1 Continued Find how the perimeter and the area of the figure change when its dimensions change. P = 2(l + w) = 2(4 + 2) P = 2(l + w). = 2(2 + 1) Course 1 10-4 Comparing Perimeter and Area = 2(6) = 12 = 2(3) = 6 The perimeter is 12 in. The perimeter is 6 in. Use the formula for perimeter of a rectangle. Substitute for l and w. Simplify.

= 4 x 2 = 8 A = lw The perimeter is divided by 2, and the area is divided by 4. Course 1 10-4 Comparing Perimeter and Area A = lw = 2 The area is 8 in 2.The area is 2 in 2. Use the formula for area of a rectangle. Substitute for l and w. = 2 x 1 Simplify. Additional Example 1 Continued Find how the perimeter and the area of the figure change when its dimensions change.

Check It Out: Example 1 Find how the perimeter and the area of the figure change when its dimensions change. Course 1 10-4 Comparing Perimeter and Area The original figure is 2 x 2 in. rectangle. The larger figure is a 4 x 4 in. rectangle. Draw a model of the two figures on graph paper. Label the dimensions. = 1 inch

P = 2(l + w) = 2(2 + 2) P = 2(l + w). = 2(4 + 4) Course 1 10-4 Comparing Perimeter and Area = 2(4) = 8 = 2(8) = 16 The perimeter is 8 in. The perimeter is 16 in. Use the formula for perimeter of a rectangle. Substitute for l and w. Simplify. Check It Out: Example 1 Continued Find how the perimeter and the area of the figure change when its dimensions change.

= 2 x 2 = 4 A = lw The perimeter is multiplied by 2, and the area is multiplied by 4. Course 1 10-4 Comparing Perimeter and Area A = lw = 16 The area is 4 in 2.The area is 16 in 2. Use the formula for area of a rectangle. Substitute for l and w. = 4 x 4 Simplify. Check It Out: Example 1 Continued Find how the perimeter and the area of the figure change when its dimensions change.

Additional Example 2: Application Draw a rectangle whose dimensions are 4 times as large as the given rectangle. How do the perimeter and area change? Multiply each dimension by 4.P = 10 cm A = 6 cm 2 P = 40 cm A = 96 cm 2 When the dimensions of the rectangle are multiplied by 4, the perimeter is multiplied by 4, and the area is multiplied by 16, or 4 2. 3 cm 2 cm 8 cm 12 cm Course 1 10-4 Comparing Perimeter and Area

Check It Out: Example 2 Draw a rectangle whose dimensions are 2 times as large as the given rectangle. How do the perimeter and area change? Multiply each dimension by 2.P = 16 cm A = 15 cm 2 P = 32 cm A = 60 cm 2 When the dimensions of the rectangle are multiplied by 2, the perimeter is multiplied by 2, and the area is multiplied by 4, or 2 2. 5 cm 3 cm 6 cm 10 cm Course 1 10-4 Comparing Perimeter and Area

Lesson Quiz Find how the perimeter and area of the triangle change when its dimensions change. The perimeter is multiplied by 2, and the area is multiplied by 4; perimeter = 24, area = 24; perimeter = 48, area = 96. Insert Lesson Title Here Course 1 10-4 Comparing Perimeter and Area

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