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Consider the triangle shown below where m∠C=50∘, b=11 cm, and a=23 cm.Use the Law of Cosines to determine the value of x (the length of AB in cm).x=

Consider the triangle shown below where m∠C=50∘, b=11 cm, and a=23 cm.Use the Law-example-1
User Alex Bloomberg
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The Law of Cosines is:


c^2=a^2+b^2-2ab\cdot\cos C

Where "a", "b" and "c" are sides of the triangle and "C" is the angle opposite side "c".

In this case you know that:


\begin{gathered} m\angle C=50\degree \\ b=11\operatorname{cm} \\ a=23\operatorname{cm} \\ c=x \end{gathered}

Then, you can substitute values as following:


\begin{gathered} c^2=a^2+b^2-2ab\cdot\cos C \\ x^2=(23\operatorname{cm})^2+(11\operatorname{cm})^2-2(23\operatorname{cm})(11\operatorname{cm})\cdot\cos (50\degree) \end{gathered}

Finally, evaluating, you get that the answer is:


\begin{gathered} \\ x\approx18.02\operatorname{cm} \end{gathered}

User Jonahb
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