Math Problem Statement

Andi menggambar sebidang tanah milik Ayahnya dengan ukuran 6 + √5 meter dan 6 - √5 meter. Hitunglah luas sawah dan panjang diagonal tanah tersebut.

Solution

The problem shown in the image asks for the following:

  1. Calculating the area (luas sawah) of a rectangular piece of land with dimensions (6+5)m(6 + \sqrt{5}) \, \text{m} and (65)m(6 - \sqrt{5}) \, \text{m}.
  2. Finding the length of the diagonal (panjang diagonal) of the same rectangle.

Let's solve both parts:

a) Calculating the area (Luas sawah):

The area AA of a rectangle is given by the formula: A=length×widthA = \text{length} \times \text{width} Substituting the given dimensions: A=(6+5)×(65)A = (6 + \sqrt{5}) \times (6 - \sqrt{5}) This is a difference of squares, so: A=62(5)2=365=31square metersA = 6^2 - (\sqrt{5})^2 = 36 - 5 = 31 \, \text{square meters}

b) Finding the diagonal length (Panjang diagonal):

The diagonal dd of a rectangle can be found using the Pythagorean theorem: d=(length)2+(width)2d = \sqrt{(\text{length})^2 + (\text{width})^2} Here, the length and width are (6+5)(6 + \sqrt{5}) and (65)(6 - \sqrt{5}). First, calculate the squares of each:

(6+5)2=36+2×6×5+(5)2=36+125+5=41+125(6 + \sqrt{5})^2 = 36 + 2 \times 6 \times \sqrt{5} + (\sqrt{5})^2 = 36 + 12\sqrt{5} + 5 = 41 + 12\sqrt{5}

(65)2=362×6×5+(5)2=36125+5=41125(6 - \sqrt{5})^2 = 36 - 2 \times 6 \times \sqrt{5} + (\sqrt{5})^2 = 36 - 12\sqrt{5} + 5 = 41 - 12\sqrt{5}

Now, adding the two expressions: (6+5)2+(65)2=(41+125)+(41125)=82(6 + \sqrt{5})^2 + (6 - \sqrt{5})^2 = (41 + 12\sqrt{5}) + (41 - 12\sqrt{5}) = 82 Therefore, the diagonal length is: d=829.06metersd = \sqrt{82} \approx 9.06 \, \text{meters}

Final Answers:

  • a) Area = 31 square meters
  • b) Diagonal length ≈ 9.06 meters

Would you like more details or have any questions?

Related Questions:

  1. How is the formula for the area of a rectangle derived?
  2. What is the difference of squares, and how is it applied in this problem?
  3. How is the Pythagorean theorem used to find the diagonal of a rectangle?
  4. Can the area of a rectangle be negative?
  5. How does the presence of square roots affect algebraic calculations?

Tip:

When using the Pythagorean theorem, always square the sides first before summing them up to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Geometry
Algebra
Square Roots
Pythagorean Theorem
Area Calculation

Formulas

Area of a rectangle: A = length × width
Difference of squares: (a + b)(a - b) = a² - b²
Diagonal of a rectangle: d = √(length² + width²)

Theorems

Pythagorean Theorem
Difference of Squares

Suitable Grade Level

Grades 8-10