Question

Find the value of the unknown side length, to the nearest tenth of a metre.

Answer 1

Case: Cosine rule

Method:

Since the missing side is facing the only given angle, we apply cosine rule.

Let

A = 35 degrees

a = ?

b = 375 m

c = 400 m

Cosine rule:

`\begin{gathered} a^2=b^2+c^2-2bcCosA \\ a^2=375^2+400^2-2(375)(400)Cos35\degree \\ a^2=140625+160000-300000*0.8192 \\ a^2=300625-245745.61 \\ a^2=54879.39 \\ a=√(54879.39) \\ a=234.26 \end{gathered}`

Final answer: to the nearest tenth of a metre

234.3 m