Math Problem Statement

The area of a rhombus is 143 sqm. If the longer diagonal is 26 m, find the angle opposite the shorter diagonal and the length of one side of the rhombus

Solution

To solve this problem, let's first recall the formula for the area of a rhombus. The area AA of a rhombus can be calculated using the lengths of its diagonals d1d_1 and d2d_2:

A=12×d1×d2A = \frac{1}{2} \times d_1 \times d_2

Where:

  • A=143sqmA = 143 \, \text{sqm} (the given area),
  • d1=26md_1 = 26 \, \text{m} (the longer diagonal),
  • d2d_2 is the unknown shorter diagonal.

Step 1: Calculate the shorter diagonal d2d_2

Substitute the known values into the formula and solve for d2d_2:

143=12×26×d2143 = \frac{1}{2} \times 26 \times d_2

143=13×d2143 = 13 \times d_2

d2=14313=11md_2 = \frac{143}{13} = 11 \, \text{m}

Step 2: Calculate the side length of the rhombus

The diagonals of a rhombus bisect each other at right angles, so we can form two right triangles. The sides of these triangles are half of each diagonal and the side length ss of the rhombus is the hypotenuse of the triangle.

Half of the diagonals are: d12=262=13mandd22=112=5.5m\frac{d_1}{2} = \frac{26}{2} = 13 \, \text{m} \quad \text{and} \quad \frac{d_2}{2} = \frac{11}{2} = 5.5 \, \text{m}

Now, using the Pythagorean theorem: s=(d12)2+(d22)2s = \sqrt{\left( \frac{d_1}{2} \right)^2 + \left( \frac{d_2}{2} \right)^2} s=132+5.52s = \sqrt{13^2 + 5.5^2} s=169+30.25=199.2514.12ms = \sqrt{169 + 30.25} = \sqrt{199.25} \approx 14.12 \, \text{m}

So, the length of one side of the rhombus is approximately 14.12m14.12 \, \text{m}.

Step 3: Find the angle opposite the shorter diagonal

In the right triangle formed by half of each diagonal, we can use trigonometry to find the angle θ\theta opposite the shorter diagonal. Specifically, we use the tangent function:

tan(θ)=d22d12=5.513\tan(\theta) = \frac{\frac{d_2}{2}}{\frac{d_1}{2}} = \frac{5.5}{13} θ=tan1(5.513)\theta = \tan^{-1} \left( \frac{5.5}{13} \right)

Let's calculate this:

θtan1(0.4231)22.94\theta \approx \tan^{-1} (0.4231) \approx 22.94^\circ

Thus, the angle opposite the shorter diagonal is approximately 22.9422.94^\circ.

Final answers:

  • The length of one side of the rhombus is approximately 14.12m14.12 \, \text{m}.
  • The angle opposite the shorter diagonal is approximately 22.9422.94^\circ.

Would you like further details or have any questions?

Here are some related questions you might find useful:

  1. How do you calculate the area of a rhombus using its side and angle?
  2. What is the relationship between the diagonals of a rhombus?
  3. How do you find the perimeter of a rhombus given the diagonals?
  4. Can a rhombus have equal diagonals?
  5. What other properties do the angles in a rhombus have?

Tip: For rhombuses, diagonals always bisect each other at right angles, which is a useful fact for solving many problems!

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Math Problem Analysis

Mathematical Concepts

Geometry
Rhombus Properties
Pythagorean Theorem
Trigonometry

Formulas

Area of a rhombus: A = (1/2) * d1 * d2
Pythagorean theorem: s = sqrt((d1/2)^2 + (d2/2)^2)
Tangent function: tan(θ) = opposite/adjacent

Theorems

Pythagorean Theorem
Trigonometric Ratios

Suitable Grade Level

Grades 9-11