Use the Law of Cosines to solve the triangles. Round lengths to the nearest tenth and angle measures to the nearest degree. a=5, b=5, c=5 a=66, b=25, c=45

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Use the Law of Cosines to solve the triangles. Round lengths to the nearest tenth and angle measures to the nearest degree.  a=5, b=5, c=5  a=66, b=25, c=45

Alrew1959 · Accepted Answer

Step 1  The law of cosines is given by  cos⁡A=b2+c2−a22bc  cos⁡B=a2+c2−b22ac  cos⁡C=a2+b2−c22ab  Step 2  Given  a=5, b=5, c=5  Using law of cosines,  cos⁡A=(5)2+(5)2−(5)22(5)(5)  cos⁡A=25+25−2550  cos⁡A=12  A=cos−1(12)  ⇒A=60∘  cos⁡B=(5)2+(5)2−(5)22(5)(5)  cos⁡B=12  ⇒B=60∘  cos⁡C=(5)2+(5)2−(5)22(5)(5)  cos⁡C=12  ⇒C=60∘  Therefore,  A=60∘  B=60∘  C=60∘  Step 3  Given,  a=66, b=25, c=45  Using law of cosines,  cos⁡A=(25)2+(45)2−(66)22(25)(45)  cos⁡A=625+2025−43562250  cos⁡A=−8531125  A=cos−1(−8531125)  ⇒A≈139∘

Use the Law of Cosines to solve the triangles. Round

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