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Cedric drew four polygons and determined their measurements as shown below.

Use decomposition to find the area of each polygon, and then place the polygons in order from greatest to least area.

Cedric drew four polygons and determined their measurements as shown below. Use decomposition-example-1

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Arrangement of the Areas in order from greatest to least area are:

Isosceles trapezoid (25 in²) > Hexagon (22 in²) > Parallelogram (21 in²) > Rhombus (20 in²)

How to find the Areas of the Polygons?

Area of Rhombus = Base Length * Height (recall that all sides of a rhombus are the same length, hence the base is the same length 5" as the slant height)

= 5" x 4"

= 20 in²

Area of Parallelogram ,

= Base Length x height

= 7" x 3"

= 21 in²

Area of Isosceles Trapezoid

= (2 x area of each triangle ) + Area of rectangular strip

= (2)(1/2)(base of each triangle)(height) + (width of strip)(height of strip)

= (2)(1/2)[ (9-1) / 2 ] (5) + (1)(5)

= (2)(1/2) (4)(5) + (1)(5)

= 20 + 5

= 25 in²

Area of hexagon = Area of Left Rectangle + Area of Right Rectangle

= (length of left rect.)(width of left rect.) + (length of right rect.)(width of right rect.)

= (5)(6-4) + (4)(3)

= (5)(2) + (4)(3)

= 10 + 12

= 22 in²

Hence we can arrange the shapes by decreasing area:

Isosceles trapezoid (25 in²) > Hexagon (22 in²) > Parallelogram (21 in²) > Rhombus (20 in²)

User Hendrik M Halkow
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