32. Based on the measurements shown on △ABC, AB must be: A. less than 7 ft B. between 7 and 10 ft C. between 10 and 17 ft D. greater than 17 ft A 47° 10 ft C 68° 7 ft B

32. Based on the measurements shown on △ABC, AB must be: A. less than 7 ft B. between 7 and 10 ft C. between 10 and 17 ft D. greater than 17 ft A 47° 10 ft C 68° 7 ft B

Answer: C. between 10 and 17 ft

Explanation: To find the possible length of \( AB \), we use the triangle inequality theorem, which states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. Additionally, we can use the Law of Cosines to find the exact length of \( AB \).

Steps:

  1. Triangle Inequality Theorem:
  • For \( \triangle ABC \):

\[ AB + BC > AC \quad \Rightarrow \quad AB + 7 > 10 \quad \Rightarrow \quad AB > 3 \]

\[ AB + AC > BC \quad \Rightarrow \quad AB + 10 > 7 \quad \Rightarrow \quad AB > -3 \quad (\text{not useful}) \]

\[ AC + BC > AB \quad \Rightarrow \quad 10 + 7 > AB \quad \Rightarrow \quad AB < 17 \]

  1. Law of Cosines:
  • To find the exact length of \( AB \), use the Law of Cosines:

\[ AB^2 = AC^2 + BC^2 - 2 \cdot AC \cdot BC \cdot \cos(B) \]

\[ AB^2 = 10^2 + 7^2 - 2 \cdot 10 \cdot 7 \cdot \cos(68^\circ) \]

\[ AB^2 = 100 + 49 - 140 \cdot \cos(68^\circ) \]

\[ AB^2 = 149 - 140 \cdot 0.3746 \quad (\text{using } \cos(68^\circ) \approx 0.3746) \]

\[ AB^2 = 149 - 52.444 \]

\[ AB^2 = 96.556 \]

\[ AB \approx \sqrt{96.556} \approx 9.82 \]

Since \( AB \approx 9.82 \), it falls between 10 and 17 ft, making option C correct.

Related

EVALUATE Independent Practice Lesson 7.3 Homework ☐ Complete problems 1-8 below for independent practice. When you are finished, check the solutions with your teacher. 1. Order the sides from shortest to longest. S 100° 50° 30° R Q 2. Order the sides from shortest to longest. L 97° 28° 55° K J 3. Order the angles from least to greatest. L 6 9 K M 12 4. Order the angles from least to greatest. S 17 8 T R 16 5. State if the following measures can be the sides of a triangle. 12, 6, 13 6. State if the following measures can be the sides of a triangle. 9, 18, 9 7. State if the following measures can be the sides of a triangle. 8, 3, 6 8. State if the following measures can be the sides of a triangle. 11, 7, 20