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Area of composite figures
Objective: to be able to find area of composite figures and use that process to solve real life problems.
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Let’s review formulas for area
7 ft Square/ Rectangle L • W 4 ft 28 ft2 9 cm 81 cm2
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Let’s review formulas for area
Triangle ½ b • h 5 ft 4 ft 10 ft2
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Let’s review formulas for area
Circle 3.14 • r2 6 in in2
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Let’s Practice! 9.2 m 7.25 m 4.3 m 3 m 19.78 m2 21.75 m2
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Let’s Practice! 15 m 5 cm cm2 225 m2
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Way to go!
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Let’s look at some new formulas for area
Parallelogram b • h 4 ft 5 ft 7 ft 35 ft2
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Let’s practice the new formula for area
Parallelogram b • h 4 ft 6 ft 12 ft 72 ft2
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Let’s practice the new formula for area
Parallelogram b • h 3.5 in 2.5 in 8 in 28.0 in2
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Let’s look at another new formula for area
Trapezoid Just a reminder…name the only characteristic that trapezoids have. 1 set of parallel sides
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Let’s look at another new formula for area
Trapezoid ½ h(b1 + b2) 4 in 2 in 7 in 11 in2
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Let’s practice the new formula for area
Trapezoid ½ h(b1 + b2) 10 in 6 in 4 in 32 in2
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Let’s practice the new formula for area
Trapezoid ½ h(b1 + b2) 23 in 9 in 17 in 180 in2
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Let’s practice!
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Let’s look at composite figures now!
Composite Figures are made up of two or more shapes. To find the area of a composite figure, you must decompose the figure into shapes with areas that you know and then find the sum of these areas!
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Find the area of the composite figure.
Example 1 Find the area of the composite figure. The area can be separated into a semicircle and a triangle. ½ (3.14)(r2) for circle ½ (b)(h) for triangle 6 m 11 m 14.1 m + 33 m = 47.1 m2
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Find the area of the composite figure.
Example 1 20 m Find the area of the composite figure. The area can be separated into a trapezoid and a rectangle. ½ h (b1 + b2) for trapezoid L • W for square 20 m 13 m 25 m 82.5 m + 400 m = 482.5 m2
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Awesome work!
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Let’s try word problems
Pedro’s father is building a shed. How many square feet of wood is needed to build the back of the shed shown at the right? 4 ft 12 ft 15 ft 210 ft2
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What about shaded areas?
Find the area of each shape and subtract. 3 cm 7 cm 4 cm 13 cm 79 cm2
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Let’s practice!
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