Compare Perimeter: Circle (r=3cm) vs Square (side=7cm)

The radius of a circle is 3 centimeters.

The length of the side of a square is 7 centimeters.

Which shape has a larger perimeter/circumference?

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Step-by-step video solution

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00:09 Which shape has a smaller perimeter?
00:13 Let's find the perimeter of the circle first.
00:16 The circle's radius is given in the problem.
00:20 We'll use the formula: Perimeter equals 2 times pi times the radius.
00:26 Now, let's replace the radius with the given number, and calculate the perimeter.
00:37 Substitute pi with three point one four. Let's compute the result.
00:48 This value is the circle's perimeter.
00:53 Next, we'll find the perimeter of the square.
00:57 We have the length of one side of the square.
01:01 The square's perimeter is 4 times one side length.
01:08 Let's insert the side value and work out the square's perimeter.
01:21 Here is the square's perimeter.
01:28 And that's how we solve which shape has the smaller perimeter.

Step-by-step written solution

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1

Understand the problem

The radius of a circle is 3 centimeters.

The length of the side of a square is 7 centimeters.

Which shape has a larger perimeter/circumference?

2

Step-by-step solution

To solve the problem of determining which shape has a larger perimeter or circumference, let's apply the necessary formulas:

The given information is as follows:

  • Radius of the circle: r=3cm r = 3 \, \text{cm}
  • Side length of the square: s=7cm s = 7 \, \text{cm}

Step 1: Calculate the circumference of the circle

The formula for the circumference of a circle is C=2πr C = 2 \pi r . Thus, substituting the given radius, we get:

C=2π(3)=6π C = 2 \pi (3) = 6 \pi

Using an approximation for π3.14159\pi \approx 3.14159, the circumference is:

C6×3.1415918.84954cm C \approx 6 \times 3.14159 \approx 18.84954 \, \text{cm}

Step 2: Calculate the perimeter of the square

The formula for the perimeter of a square is P=4s P = 4s . Substituting the given side length, we find:

P=4×7=28cm P = 4 \times 7 = 28 \, \text{cm}

Step 3: Compare the perimeter of the square and the circumference of the circle

The calculated circumference of the circle is approximately 18.85cm 18.85 \, \text{cm} , and the perimeter of the square is 28cm 28 \, \text{cm} .

Upon comparison, 28cm 28 \, \text{cm} (perimeter of the square) is greater than 18.85cm 18.85 \, \text{cm} (circumference of the circle).

Therefore, the shape with the larger perimeter/circumference is the square.

3

Final Answer

The circle

Practice Quiz

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\( r=2 \)

Calculate the circumference.

222

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