Mathematics
Grade 7
15 min
Area between two shapes
Area between two shapes
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1
Introduction & Learning Objectives
Learning Objectives
Identify the outer and inner shapes in a given problem.
Recall and apply area formulas for basic 2D shapes (rectangles, squares, circles).
Calculate the area of a larger, outer shape.
Calculate the area of a smaller, inner shape contained within the outer shape.
Subtract the area of the inner shape from the outer shape to find the area between them.
Solve real-world problems involving the area between two shapes.
Express the final area with appropriate square units.
Imagine you're painting a wall with a window in it. How would you figure out just the area you need to paint, not including the window? 🤔
In this lesson, you'll learn how to calculate the space between two shapes, like the area of a frame around a picture or the grass around a po...
2
Key Concepts & Vocabulary
TermDefinitionExample
AreaThe amount of surface a two-dimensional shape covers, measured in square units.A square with sides of 4 cm has an area of 16 square centimeters ($16 ext{ cm}^2$).
Outer ShapeThe larger shape that completely encloses another shape.In a problem about a rectangular garden with a circular pond, the rectangular garden is the outer shape.
Inner ShapeThe smaller shape that is completely contained within a larger shape.In a problem about a rectangular garden with a circular pond, the circular pond is the inner shape.
Area Between ShapesThe region that is part of the outer shape but not part of the inner shape; found by subtracting the inner area from the outer area.The grassy area in a rectangular garden surrounding a circular pond is the 'area between shapes'...
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Core Formulas
Area of a Rectangle
$A = l \times w$
To find the area of a rectangle, multiply its length ($l$) by its width ($w$). This is used for rectangular outer or inner shapes.
Area of a Square
$A = s^2$
To find the area of a square, multiply its side length ($s$) by itself. This is a special case of a rectangle where length equals width.
Area of a Circle
$A = \pi r^2$
To find the area of a circle, multiply pi ($\pi \approx 3.14$) by the square of its radius ($r$). This is used for circular outer or inner shapes.
Area Between Two Shapes
$A_{\text{between}} = A_{\text{outer}} - A_{\text{inner}}$
To find the area of the region that is part of a larger (outer) shape but not part of a smaller (inner) shape contained within it, subtract the area of the inner shape from the...
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Challenging
A square has a side length of *x*. A circle with the largest possible radius is drawn inside it. Which expression represents the area between the square and the circle?
A.x² - πx²
B.x - π(x/2)²
C.2x - 2Ï€(x/2)
D.x² - π(x/2)²
Challenging
A rectangular patio has a length that is twice its width (l=2w). A circular hot tub with a radius of 4 feet is on the patio. The area of the patio NOT covered by the hot tub is 149.76 ft². What are the dimensions of the patio? (Use π ≈ 3.14)
A.20 ft by 10 ft
B.18 ft by 9 ft
C.22 ft by 11 ft
D.100 ft by 50 ft
Challenging
A square photo with a side of 10 inches is placed on a mat that creates a 2-inch border. This matted photo is then placed in a frame that adds another 1-inch border. What is the area of the wooden frame only?
A.196 in²
B.60 in²
C.96 in²
D.256 in²
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