Part A. In the given problem a triangle is formed. Since we are required to determine one of its sides given the opposite angle and the other two sides we can use the cosine law:
[tex]c^2=a^2+b^2-2ab\cos\theta[/tex]
Where:
[tex]\begin{gathered} c,a,b\text{ = sides} \\ \theta=\text{ opposite angle} \end{gathered}[/tex]
Now, we plug in the values:
[tex]d^2=7^2+5.5^2-2(7)(5.5)\cos118[/tex]
Now, we solve the operations:
[tex]d^2=115.4[/tex]
Now, we take the square root to both sides:
[tex]\begin{gathered} d=\sqrt{115.4} \\ d=10.7 \end{gathered}[/tex]
Therefore, the distance between the cars is 10.7 feet.
Part B. We are given the following situation:
We will apply the coside law using the angle "x" as the opposite angle:
[tex]10.7^2=10^2+13^2-2(10)(13)\cos x[/tex]
Now, we solve the operations:
[tex]114.49=100+169-260\cos x[/tex]
Now, we solve the addition:
[tex]114.49=269-260\cos x[/tex]
Now, we subtract 269 from both sides:
[tex]\begin{gathered} 114.49-269=-260\cos x \\ -145.51=-260\cos x \end{gathered}[/tex]
Now, we divide both sides by -260:
[tex]\frac{-145.51}{-260}=\cos x[/tex]
Now, we take the inverse function of the cosine:
[tex]\cos^{-1}(\frac{-145.51}{-260})=x[/tex]
Solving the operations:
[tex]55.97=x[/tex]
Therefore, angle "x" is 55.97 degrees.
Now, we use angle "y" as the opposite angle. Applying the cosine law we get:
[tex]13^2=10^2+10.7^2-2(10)(10.7)\cos y[/tex]
Solving the operations:
[tex]169=214.5-214\cos y[/tex]
Now, we subtract 214.5 from both sides:
[tex]\begin{gathered} 169-214.5=-214\cos y \\ -45.5=-214\cos y \end{gathered}[/tex]
Now, we divide both sides by 214
[tex]\frac{-45.5}{-214}=\cos y[/tex]
Now, we take the inverse function of the cosine:
[tex]\begin{gathered} \cos^{-1}(-\frac{45.5}{-214})=y \\ \\ 77.75=y \end{gathered}[/tex]
Therefore, angle "y" is 77.72 °
To determine angle "z" we will use the fact that the sum of the interior angles of a triangle always adds up to 180:
[tex]\begin{gathered} x+y+z=180 \\ \end{gathered}[/tex]
Plugging in the values:
[tex]55.97+77.72+z=180[/tex]
Solving the operations:
[tex]133.69+z=180[/tex]
Now, we subtract 133.69 from both sides:
[tex]\begin{gathered} z=180-133.69 \\ z=46.31 \end{gathered}[/tex]
Therefore, angle "z" is 46.31 degrees.