Math Problem Statement

Find the lengths represented by x and y in the truss shown in the diagram.

Find the lengths represented by x and y in the truss shown in the diagram.

Solution

To solve for the lengths xx and yy in the given triangle diagram, we can break the problem down step by step.

Information from the diagram:

  • The total length of the base of the truss is 11.2ft11.2 \, \text{ft}.
  • One section of the base is 4.8ft4.8 \, \text{ft}, corresponding to the leg next to the angle 4242^\circ.
  • The hypotenuse of this right triangle is 6.3ft6.3 \, \text{ft} (labeled in the diagram).
  • We have two unknowns: xx (the vertical height of the triangle on the right) and yy (the diagonal hypotenuse on the left triangle).

To find xx (the height):

We can use trigonometry in the right triangle on the right-hand side. Specifically, we can apply the sine and cosine functions:

  • Using the angle 4242^\circ and the known side 6.3ft6.3 \, \text{ft} (the hypotenuse), we can use the sine function to find xx, since xx is opposite the angle: sin(42)=x6.3\sin(42^\circ) = \frac{x}{6.3} Solving for xx: x=6.3×sin(42)x = 6.3 \times \sin(42^\circ)

x6.3×0.66914.21ftx \approx 6.3 \times 0.6691 \approx 4.21 \, \text{ft}

To find yy (the diagonal on the left side):

Next, we need to find yy. Since the entire base of the triangle is 11.2ft11.2 \, \text{ft}, and we already know the right portion of the base is 4.8ft4.8 \, \text{ft}, the left portion of the base will be: Left base=11.24.8=6.4ft\text{Left base} = 11.2 - 4.8 = 6.4 \, \text{ft} Now we have a right triangle on the left side where we know the base is 6.4ft6.4 \, \text{ft} and the height is 4.21ft4.21 \, \text{ft} (the same as xx). To find yy (the hypotenuse of the left triangle), we can use the Pythagorean theorem: y2=6.42+4.212y^2 = 6.4^2 + 4.21^2

y2=40.96+17.72y^2 = 40.96 + 17.72 y2=58.68y^2 = 58.68 y58.687.66fty \approx \sqrt{58.68} \approx 7.66 \, \text{ft}

Final Answer:

  • x4.21ftx \approx 4.21 \, \text{ft}
  • y7.66fty \approx 7.66 \, \text{ft}

Let me know if you would like further details or have any questions.


Here are some related questions for further practice:

  1. How would the result change if the angle was different, say 3030^\circ?
  2. What is the area of the entire truss?
  3. How could we find the perimeter of the truss?
  4. If the height doubled, how would that impact the lengths xx and yy?
  5. What would the length of yy be if the base on the left side was longer?

Tip: When solving right triangles, it's helpful to remember the basic trigonometric ratios—sine, cosine, and tangent—depending on which sides and angles you know.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Right Triangle Properties
Pythagorean Theorem

Formulas

sin(θ) = opposite/hypotenuse
cos(θ) = adjacent/hypotenuse
Pythagorean theorem: a^2 + b^2 = c^2

Theorems

Trigonometric Ratios
Pythagorean Theorem

Suitable Grade Level

Grades 9-11