Estimating and Finding Area Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem...
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Estimating and Finding Area Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day
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Transcript of Estimating and Finding Area Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem...
Estimating and Finding Area
Course 1
Warm UpWarm Up
Lesson PresentationLesson Presentation
Problem of the DayProblem of the Day
Learn to estimate the area of irregular figures and to find the area of rectangles and parallelograms.
Course 1
Estimating and Finding Area
TEKS 6.8.B: Measurement: select and use appropriate units, tools or formulas to measure and to solve problems…
Vocabulary
area
Insert Lesson Title Here
Course 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
Estimating and Finding Area
Course 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
Estimating and Finding Area
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.
Course 1
Estimating and Finding Area
Additional Example 3: Finding the Area of a Parallelogram
Find the area of the parallelogram.
Write the formula.
Multiply.
A = bh
2 ft12
A = 2 • 112__ 1
4__ Substitute 2 for b
and 1 for h.
12__
14__
A = •52__ 5
4__
A = or 325 8
___ 18__
The area is 3 ft2. 18__
14
1 ft
Course 1
Estimating and Finding Area
Course 1
Estimating and Finding Area
You can divide any parallelogram into two congruent triangles. So the area of each triangle is half the area of the parallelogram.
Base
HeightHeight
Base
Area of Triangles
Course 1
Estimating and Finding Area
AREA OF A TRIANGLE
b
A = 12
bhThe area A of a triangleis half the product of itsbase b and its height h.
h
Course 1
Estimating and Finding Area
Find the area of the triangle.
Additional Example 1A: Finding the Area of a Triangle
A = 12
bh Write the formula.
A = 12
(20 · 12) Substitute 20 for b and 12 for h.
A = 120
The area is 120 ft2.
A = 12
(240) Multiply.
Course 1
Estimating and Finding Area
Find the area of the triangle.
Additional Example 1B: Finding the Area of a Triangle
A = 12
bh Write the formula.
A = 12
(30 · 24) Substitute 30 for b and 24 for h.
A = 360
The area is 360 in2.
A = 12
(720) Multiply.
Course 1
Estimating and Finding Area
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Course 1
Estimating and Finding Area
Additional Example 1A: Estimating the Area of a Circle
Estimate the area of the circle. Use 3 to approximate pi.
A ≈ 3 • 202
A ≈ 1200 m2
19.7 m
A = r2 Write the formula for area.
Replace with 3 and r with 20.
A ≈ 3 • 400Use the order of operations.
Multiply.
Course 1
Estimating and Finding Area
Additional Example 1B: Estimating the Area of a Circle
Estimate the area of the circle. Use 3 to approximate pi.
r = 28 ÷ 2
A ≈ 3 • 142
28 m
A = r2 Write the formula for area.
Replace with 3 and r with 14.
r = 14
Use the order of operations.
Divide.
r = d ÷ 2 The length of the radius is half the length of the diameter.
A ≈ 3 • 196
A ≈ 588 m2 Multiply.
Course 1
Estimating and Finding AreaAdditional Example 1A: Finding Areas of Composite
Figures
Find the area of the polygon.
Think: Break the polygon apart into rectangles.
Find the area of each rectangle.
1.7 cm
4.9 cm 1.3 cm
2.1 cm
Course 1
Estimating and Finding AreaAdditional Example 1A Continued
A = lw A = lw
A = 4.9 • 1.7 A = 2.1 • 1.3Write the formula for the area of a rectangle.A = 8.33 A = 2.73
8.33 + 2.73 = 11.06 Add to find the total area.
The area of the polygon is 11.06 cm2.
1.7 cm
4.9 cm
1.3 cm
2.1 cm
Course 1
Estimating and Finding Area
Think: Break the figure apart into a rectangle and a triangle.
Find the area of each polygon.
Additional Example 1B: Finding Areas of Composite Figures
Find the area of the polygon.
Course 1
Estimating and Finding AreaAdditional Example 1B Continued
A = lw
A = 28 • 24
A = 672 A = 168
672 + 168 = 840 Add to find the total area of the polygon.
The area of the polygon is 840 ft2.
A = bh12__
A = • 28 • 1212__
Course 1
Estimating and Finding Area
Lesson Quiz
1. Find the area of the figure shown.
220 units2
2. Phillip designed a countertop. Use the coordinate grid to find its area.
30 units2
