10-1 Estimating and Finding Area

Course 1

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Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

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

Course 1

10-1 Estimating and Finding Area

Learn to estimate the area of irregular figures and to find the area of rectangles.

Course 1

10-1 Estimating and Finding Area

Vocabulary

area

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Course 1

10-1 Estimating and Finding Area

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

Course 1

10-1 Estimating and Finding Area

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

The area of the figure is about 30 mi .2

Course 1

10-1 Estimating and Finding Area

Check It Out: Example 1

Estimate the are of the figure.

Count full squares: 11 red squares.

Count almost-full squares: 5 green squares.Count squares that are about half-full: 4 blue squares = 2 full squares.Do not count almost empty yellow squares.Add. 11 + 5 + 2 = 18

The area of the figure is about 18 mi .2

= mi2

Course 1

10-1 Estimating and Finding Area

Course 1

10-1 Estimating and Finding Area

Additional Example 2: Finding 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 about 135 in2.

15 in.

9 in.

Course 1

10-1 Estimating and Finding Area

Check It Out: 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 about 91 in2.

13 in.

7 in.

Course 1

10-1 Estimating and Finding Area

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?

Substitute for l and w in A = lw.

Use the order of operations.

The area of the kitchen to be tiled is 203 ft2.

floor area

To find the area to be tiled, subtract the area of the island from the area of the floor.

Course 1

10-1 Estimating and Finding Area

kitchen area to be tiledisland =

(13 • 17) (3 • 6) n =

221 – 18 = 203

Lesson Quiz

Find the area of each figure.

1.

2. What is the area of a parallelogram with base 16

in. and height 10 in.?

3. 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?

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4.5 m

9.2 m 41.4 m2

160 in2

Course 1

10-1 Estimating and Finding Area