Math Problem Statement

AB = 6 cm, AC = 12 cm, ∠DAB = 55° Calculate the length of CD. Give your answer to 3 significant figures.

Solution

It seems that the problem involves a triangle where we are tasked to find the length of side CDCD. Here's a breakdown based on the image:

  • AB=6cmAB = 6 \, \text{cm}
  • AC=12cmAC = 12 \, \text{cm}
  • DAB=55\angle DAB = 55^\circ
  • We need to calculate the length of CDCD to 3 significant figures.

Steps to Solve:

  1. Use the Law of Cosines: Since we have the angle between two known sides ABAB and ACAC, we can apply the law of cosines: CD2=AB2+AC22ABACcos(DAB)CD^2 = AB^2 + AC^2 - 2 \cdot AB \cdot AC \cdot \cos(\angle DAB)
  2. Substitute the values: CD2=62+1222612cos(55)CD^2 = 6^2 + 12^2 - 2 \cdot 6 \cdot 12 \cdot \cos(55^\circ)
  3. Simplify the equation and solve for CDCD.

Let me calculate this for you.The length of CDCD is approximately 9.87cm9.87 \, \text{cm} when rounded to 3 significant figures.

Would you like more details or have any questions?

Here are 5 related questions to deepen your understanding:

  1. How does the law of cosines relate to the Pythagorean theorem?
  2. What happens when the angle in the law of cosines is 9090^\circ?
  3. Can you apply the law of sines to this triangle? If so, how?
  4. How can we solve a triangle when we know only two angles and one side?
  5. What is the significance of using radians in trigonometric calculations?

Tip: Always ensure your calculator is set to the correct mode (degrees or radians) based on the angle units you're working with.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Triangle Properties

Formulas

Law of Cosines: c² = a² + b² - 2ab * cos(θ)

Theorems

Law of Cosines

Suitable Grade Level

Grades 9-10