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Calculate the perimeters of the following shapes, using pi = 22/7 where needed. Shape 1 is a semicircle with diameter 14 cm. Shape 2 is composed of a quarter circle, a semicircle, and a straight line

Mathematics

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here are the perimeters of the shapes:

1)
This shape is a semicircle.

Step 1: Calculate the length of the curved part.
The diameter (dd) is 14 cm14 \text{ cm}. The curved part is half the circumference of a circle. The formula for the circumference of a circle is C=πdC = \pi d. We are given π=227\pi = \frac{22}{7}.

Length of curved part=12πd=12×227×14 cm\text{Length of curved part} = \frac{1}{2} \pi d = \frac{1}{2} \times \frac{22}{7} \times 14 \text{ cm} Length of curved part=11×2 cm=22 cm\text{Length of curved part} = 11 \times 2 \text{ cm} = 22 \text{ cm}

Step 2: Calculate the total perimeter.
The perimeter is the sum of the straight side (diameter) and the curved part.

Perimeter=14 cm+22 cm\text{Perimeter} = 14 \text{ cm} + 22 \text{ cm} Perimeter=36 cm\text{Perimeter} = 36 \text{ cm}

The perimeter of shape 1 is 36 cm\boxed{\text{36 cm}}.

2)
This shape consists of a quarter circle, a semicircle, and a straight line segment.

Step 1: Identify the dimensions.
The straight line segment is 7 cm7 \text{ cm}. This is the radius of the quarter circle (r1=7 cmr_1 = 7 \text{ cm}) and also the diameter of the semicircle (d2=7 cmd_2 = 7 \text{ cm}).

Step 2: Calculate the arc length of the quarter circle.

Arc length of quarter circle=14(2πr1)=12πr1=12×227×7 cm\text{Arc length of quarter circle} = \frac{1}{4} (2 \pi r_1) = \frac{1}{2} \pi r_1 = \frac{1}{2} \times \frac{22}{7} \times 7 \text{ cm} Arc length of quarter circle=11 cm\text{Arc length of quarter circle} = 11 \text{ cm}

Step 3: Calculate the arc length of the semicircle.

Arc length of semicircle=12(πd2)=12×227×7 cm\text{Arc length of semicircle} = \frac{1}{2} (\pi d_2) = \frac{1}{2} \times \frac{22}{7} \times 7 \text{ cm} Arc length of semicircle=11 cm\text{Arc length of semicircle} = 11 \text{ cm}

Step 4: Calculate the total perimeter.

Perimeter=(arc length of quarter circle)+(arc length of semicircle)+(straight line segment)\text{Perimeter} = (\text{arc length of quarter circle}) + (\text{arc length of semicircle}) + (\text{straight line segment}) Perimeter=11 cm+11 cm+7 cm\text{Perimeter} = 11 \text{ cm} + 11 \text{ cm} + 7 \text{ cm} Perimeter=29 cm\text{Perimeter} = 29 \text{ cm}

The perimeter of shape 2 is 29 cm\boxed{\text{29 cm}}.

3)
This shape is a rectangle with a semicircle cut out from the top.

Step 1: Identify the lengths of the straight sides.
The bottom side is 9 cm9 \text{ cm}. The two vertical sides are 5 cm5 \text{ cm} each. The two small straight segments on the top are 1 cm1 \text{ cm} each.

Step 2: Determine the diameter of the inner semicircle.
The total length of the top edge of the rectangle is 9 cm9 \text{ cm}. The two small straight segments are 1 cm1 \text{ cm} each. So, the diameter of the semicircle (dd) is 9 cm−1 cm−1 cm=7 cm9 \text{ cm} - 1 \text{ cm} - 1 \text{ cm} = 7 \text{ cm}.

Step 3: Calculate the arc length of the inner semicircle.

Arc length of semicircle=12πd=12×227×7 cm\text{Arc length of semicircle} = \frac{1}{2} \pi d = \frac{1}{2} \times \frac{22}{7} \times 7 \text{ cm} Arc length of semicircle=11 cm\text{Arc length of semicircle} = 11 \text{ cm}

Step 4: Calculate the total perimeter.

Perimeter=(bottom side)+(two vertical sides)+(two top straight segments)+(arc length of inner semicircle)\text{Perimeter} = (\text{bottom side}) + (\text{two vertical sides}) + (\text{two top straight segments}) + (\text{arc length of inner semicircle}) Perimeter=9 cm+(2×5 cm)+(2×1 cm)+11 cm\text{Perimeter} = 9 \text{ cm} + (2 \times 5 \text{ cm}) + (2 \times 1 \text{ cm}) + 11 \text{ cm} Perimeter=9 cm+10 cm+2 cm+11 cm\text{Perimeter} = 9 \text{ cm} + 10 \text{ cm} + 2 \text{ cm} + 11 \text{ cm} Perimeter=32 cm\text{Perimeter} = 32 \text{ cm}

The perimeter of shape 3 is 32 cm\boxed{\text{32 cm}}.

4)
This shape is composed of four semicircles.

Step 1: Identify the diameter of each semicircle.
The dashed lines indicate a central square with sides of 7 cm7 \text{ cm}. Each semicircle has a diameter (dd) equal to the side of this square, so d=7 cmd = 7 \text{ cm}.

Step 2: Calculate the arc length of one semicircle.

Arc length of one semicircle=12πd=12×227×7 cm\text{Arc length of one semicircle} = \frac{1}{2} \pi d = \frac{1}{2} \times \frac{22}{7} \times 7 \text{ cm} Arc length of one semicircle=11 cm\text{Arc length of one semicircle} = 11 \text{ cm}

Step 3: Calculate the total perimeter.
Since there are four such semicircles, the total perimeter is four times the arc length of one semicircle.

Perimeter=4×11 cm\text{Perimeter} = 4 \times 11 \text{ cm} Perimeter=44 cm\text{Perimeter} = 44 \text{ cm}

The perimeter of shape 4 is 44 cm\boxed{\text{44 cm}}.

5)
This shape is a rectangle with two semicircles on its ends.

Step 1: Identify the dimensions.
The '7' indicates the length of the straight rectangular part is 7 cm7 \text{ cm}. The vertical dashed lines show that the diameter of each semicircle (dd) is also 7 cm7 \text{ cm}.

Step 2: Calculate the total perimeter.
The perimeter consists of two straight sides and the circumference of one full circle (formed by the two semicircles).

Perimeter=(2×length of straight side)+(πd)\text{Perimeter} = (2 \times \text{length of straight side}) + (\pi d)
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