Calculate Square Perimeter Using Diagonal Expression: 3√2×(3²-2³)-2√2

Square Properties with Diagonal Calculations

ABCD is a square.

The length of the diagonal:
32×(3223)22 3\sqrt{2}\times\left(3^2-2^3\right)-2\sqrt{2}

AAABBBCCCDDDWhat is the perimeter of the square ABCD?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:15 Let's find the perimeter of the square.
00:20 Since all sides are equal, let's call each side A.
00:24 Remember, every angle in a square is a right angle.
00:28 We'll apply the Pythagorean theorem in triangle A D B now.
00:36 Substitute the given values into the formula to find A.
00:59 Solve the powers and then substitute.
01:14 First, always solve what's in the parentheses.
01:35 Next, subtract what's needed.
01:38 Remember, the square root of a number squared is just that numb er.
01:44 Let's isolate side A.
01:49 This gives us the length of side A.
01:56 To find the perimeter, multiply four times A since all sides are eq ual.
02:02 Put in the length we found for A to get the perimeter.
02:06 And, that's the solution! Great job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

ABCD is a square.

The length of the diagonal:
32×(3223)22 3\sqrt{2}\times\left(3^2-2^3\right)-2\sqrt{2}

AAABBBCCCDDDWhat is the perimeter of the square ABCD?

2

Step-by-step solution

The problem involves the square ABCD, and we need to determine its perimeter, given the expression for the length of its diagonal. Here's the step-by-step solution:

Let's denote the side of the square ABCD as s s . The diagonal of a square can be calculated using Pythagoras' theorem as:

  • d=s2 d = s\sqrt{2}

The problem provides an expression for the length of the diagonal:

  • 32×(3223)22 3\sqrt{2}\times(3^2-2^3)-2\sqrt{2}

Let's simplify this expression step by step.

First, calculate the powers:

  • 32=9 3^2 = 9

  • 23=8 2^3 = 8

Subtract these values:

  • 3223=98=1 3^2 - 2^3 = 9 - 8 = 1

Substitute back into the expression for the diagonal:

  • 32×122 3\sqrt{2} \times 1 - 2\sqrt{2}

This simplifies to:

  • 3222 3\sqrt{2} - 2\sqrt{2}

  • (32)2=12=2 (3 - 2)\sqrt{2} = 1\sqrt{2} = \sqrt{2}

So, the length of the diagonal is 2 \sqrt{2} .

We know from the formula for the diagonal of a square that d=s2 d = s\sqrt{2} . Given d=2 d = \sqrt{2} , we can equate:

  • s2=2 s\sqrt{2} = \sqrt{2}

Thus:

  • s=1 s = 1

Therefore, the perimeter of the square ABCD is:

  • 4×s=4×1=4 4 \times s = 4 \times 1 = 4

Hence, the perimeter of the square ABCD is 4.

3

Final Answer

4

Key Points to Remember

Essential concepts to master this topic
  • Diagonal Formula: For any square with side s, diagonal equals s2 s\sqrt{2}
  • Order of Operations: Calculate powers first: 32=9 3^2 = 9 and 23=8 2^3 = 8
  • Verification: Check that 1×2=2 1 \times \sqrt{2} = \sqrt{2} matches diagonal expression ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting order of operations in complex expressions
    Don't calculate 32×32 3\sqrt{2} \times 3^2 before evaluating the parentheses = wrong diagonal length! This ignores PEMDAS rules. Always evaluate parentheses first, then powers, then multiply and subtract from left to right.

Practice Quiz

Test your knowledge with interactive questions

\( 6+\sqrt{64}-4= \)

FAQ

Everything you need to know about this question

Why does a square's diagonal equal s2 s\sqrt{2} ?

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This comes from the Pythagorean theorem! In a square, the diagonal forms the hypotenuse of a right triangle with two equal sides. So d2=s2+s2=2s2 d^2 = s^2 + s^2 = 2s^2 , which means d=s2 d = s\sqrt{2} .

Do I need to simplify 3222 3\sqrt{2} - 2\sqrt{2} first?

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Yes! These are like terms because they both have 2 \sqrt{2} . Combine them: (32)2=12=2 (3-2)\sqrt{2} = 1\sqrt{2} = \sqrt{2} .

What if I calculated 3223 3^2 - 2^3 wrong?

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Double-check: 32=3×3=9 3^2 = 3 \times 3 = 9 and 23=2×2×2=8 2^3 = 2 \times 2 \times 2 = 8 . So 98=1 9 - 8 = 1 . Any other result will give you the wrong diagonal length!

How do I find the side length from the diagonal?

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Use the diagonal formula backwards! If d=s2 d = s\sqrt{2} , then s=d2 s = \frac{d}{\sqrt{2}} . In this problem: s=22=1 s = \frac{\sqrt{2}}{\sqrt{2}} = 1 .

Why is the perimeter 4 times the side length?

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A square has 4 equal sides, so perimeter = 4 × side length. With side length 1, the perimeter is 4×1=4 4 \times 1 = 4 .

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