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Question 9 of 10 Select the angle that correctly completes the law of cosines for this triangle. 52 +132 - 2(5)(13)cos __ = 122 67° 13 23° 90 12 O A. 90° B. 67° O C. 23°

Question 9 of 10 Select the angle that correctly completes the law of cosines for this triangle 52 132 2513cos 122 67 13 23 90 12 O A 90 B 67 O C 23 class=

Respuesta :

[tex]5^2+13^2-2(5)(13)\cos x=12^2[/tex]

where x is the missing angle,

we can solve the operations and find x

[tex]\begin{gathered} -130\cos x=12^2-13^2-5^2 \\ -130\cos x=-50 \\ \cos x=\frac{-50}{-130} \\ \\ x=\cos ^{-1}(\frac{5}{13}) \\ \\ x=67.38 \end{gathered}[/tex]

so the right value is 67, option B

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