Math Problem Statement

Use the Law of Sines to solve for all possible triangles that satisfy the given conditions. (If an answer does not exist, enter DNE. Round your answers to one decimal place. Below, enter your answers so that ∠B1 is larger than ∠B2.)

a = 36,    c = 48,    ∠A = 31°

B1 =

  °

    

B2 =

  °

C1 =

  °

    

C2 =

  °

b1 =

    

b2 =

Solution

To solve the triangle using the Law of Sines, we will start by calculating the possible values for angle BB and then determine the other sides and angles of the triangle.

Given:

  • a=36a = 36
  • c=48c = 48
  • A=31\angle A = 31^\circ

Step 1: Use the Law of Sines

The Law of Sines states: asin(A)=bsin(B)=csin(C)\frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)} Substitute the known values for aa, cc, and A\angle A: 36sin(31)=48sin(C)\frac{36}{\sin(31^\circ)} = \frac{48}{\sin(C)} First, calculate the value of sin(31)\sin(31^\circ): sin(31)0.515\sin(31^\circ) \approx 0.515 Thus, 360.51569.9\frac{36}{0.515} \approx 69.9 Now, apply the Law of Sines to find sin(C)\sin(C): 69.948=1sin(C)\frac{69.9}{48} = \frac{1}{\sin(C)} This gives: sin(C)=4869.90.686\sin(C) = \frac{48}{69.9} \approx 0.686

Step 2: Solve for C\angle C

Using the inverse sine function, calculate C\angle C: C1=sin1(0.686)43.4\angle C_1 = \sin^{-1}(0.686) \approx 43.4^\circ Now, calculate the other possible solution for C\angle C (since sine has two possible values in the range of 0 to 180 degrees): C2=18043.4136.6\angle C_2 = 180^\circ - 43.4^\circ \approx 136.6^\circ

Step 3: Solve for B\angle B

Using the fact that the sum of angles in a triangle is 180180^\circ, calculate B1\angle B_1 and B2\angle B_2:

For B1\angle B_1: B1=1803143.4=105.6\angle B_1 = 180^\circ - 31^\circ - 43.4^\circ = 105.6^\circ

For B2\angle B_2: B2=18031136.6=12.4\angle B_2 = 180^\circ - 31^\circ - 136.6^\circ = 12.4^\circ

Step 4: Solve for b1b_1 and b2b_2

Using the Law of Sines again, solve for b1b_1 and b2b_2:

For b1b_1: b1sin(105.6)=36sin(31)\frac{b_1}{\sin(105.6^\circ)} = \frac{36}{\sin(31^\circ)} b1=36sin(105.6)0.515360.9650.51567.4b_1 = \frac{36 \cdot \sin(105.6^\circ)}{0.515} \approx \frac{36 \cdot 0.965}{0.515} \approx 67.4

For b2b_2: b2sin(12.4)=36sin(31)\frac{b_2}{\sin(12.4^\circ)} = \frac{36}{\sin(31^\circ)} b2=36sin(12.4)0.515360.2150.51515.0b_2 = \frac{36 \cdot \sin(12.4^\circ)}{0.515} \approx \frac{36 \cdot 0.215}{0.515} \approx 15.0

Final Answers:

  • B1=105.6\angle B_1 = 105.6^\circ
  • B2=12.4\angle B_2 = 12.4^\circ
  • C1=43.4\angle C_1 = 43.4^\circ
  • C2=136.6\angle C_2 = 136.6^\circ
  • b1=67.4b_1 = 67.4
  • b2=15.0b_2 = 15.0

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

Here are five related questions for further exploration:

  1. How does the Law of Cosines differ from the Law of Sines?
  2. What happens when there are no possible triangles?
  3. How do we determine if a triangle is ambiguous using the Law of Sines?
  4. Can the Law of Sines be used in right triangles?
  5. How would the calculations change if A\angle A was larger?

Tip: The Law of Sines can yield two possible triangles, but one must always check the validity of both using the angle sum property of triangles.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Law of Sines
Ambiguous Case
Triangle Geometry

Formulas

Law of Sines: a/sin(A) = b/sin(B) = c/sin(C)
Angle Sum Property of Triangles: A + B + C = 180°

Theorems

Law of Sines

Suitable Grade Level

Grades 10-12