Math Problem Statement

Using the sine rule, calculate the length d. Given: angles 71°, 67°, 42°, and side opposite 42° is 36.5 m.

Solution

To solve this problem using the sine rule, we will apply the formula:

asin(A)=bsin(B)=csin(C)\frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)}

where aa, bb, and cc are the sides of the triangle, and AA, BB, and CC are the angles opposite these sides, respectively.

Step-by-step solution:

  1. Labeling the triangle:

    • We are asked to find dd, which is the side opposite the 6767^\circ angle.
    • The known side is 36.5 m, which is opposite the 4242^\circ angle.
  2. Set up the sine rule equation: dsin(67)=36.5sin(42)\frac{d}{\sin(67^\circ)} = \frac{36.5}{\sin(42^\circ)}

  3. Solve for dd: Rearrange the equation to solve for dd: d=36.5sin(67)sin(42)d = \frac{36.5 \cdot \sin(67^\circ)}{\sin(42^\circ)}

  4. Substitute the values of the sines: Using a calculator:

    • sin(67)0.921\sin(67^\circ) \approx 0.921
    • sin(42)0.669\sin(42^\circ) \approx 0.669

    So: d=36.50.9210.66933.61650.66950.26md = \frac{36.5 \cdot 0.921}{0.669} \approx \frac{33.6165}{0.669} \approx 50.26 \, \text{m}

Final answer:

The length of dd is approximately 50.26 m (to 2 decimal places).


Would you like more details or have any further questions?

Here are some related questions you might find interesting:

  1. What is the sine rule, and how does it apply to non-right-angled triangles?
  2. How would you solve this problem if a different side length were given?
  3. Can the sine rule be used in right-angled triangles?
  4. How can you calculate the third side of the triangle using the cosine rule?
  5. What happens if the angles given are incorrect or don't add up to 180°?

Tip: Always make sure the sum of the angles in a triangle equals 180°, as this helps verify the correctness of your given information.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Sine Rule
Triangle

Formulas

\frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)}

Theorems

Sine Rule

Suitable Grade Level

Grades 9-11