B. Use the Law of Cosines 1. Calculate the length of side c. С 120° a = 7 b = 6 C С VALUATION

[tex] \large \bold{\blue{Problem:}} [/tex] Calculate the length of side c. С=120° a=7 b=6
[tex] \large \bold{\blue{Solution:}} [/tex] The oblique triangle has the given of two sides and an included angle (SAS). Find side c using the law of cosines.
[tex] \large \therefore \underline{\boxed{\tt \purple{c = 11.27 \: units}}} [/tex]
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[tex]\huge\underline { \mathcal{Answer}}{:}[/tex]
[tex]c = 10[/tex]
ᴀs sʜᴏᴡɴ ɪɴ ᴛʜᴇ ғɪɢᴜʀᴇ . a = 7, b = 4, C = 120°
sᴏ
[tex] {c}^{2} = {a}^{2} + {b}^{2} - 2abcos[/tex]
C
[tex] = 49 + 16 - 56 \times ( - \frac{1}{2} )[/tex]
[tex] = 93[/tex]
sᴏ
[tex]c = \sqrt{93} = 10[/tex]
(ɴᴏᴛᴇ : ᴏᴡɴ ᴀɴsᴡᴇʀ )
[tex]\huge\orange{\boxed{{ᴍᴀᴛʜǫᴜᴇ̈ᴇ̈ɴ}}}[/tex]