Question

Laws of sine and cosine

Answer 1

Law of Sines

`\displaystyle (sin∠C)/(c) = (sin∠B)/(b) = (sin∠A)/(a) \\ \\ (sin\:40°)/(5) = (sin∠C)/(7) → (7sin\:40°)/(5) = sin∠C → 0,8999026535... = sin∠C → 64,14527443...° = sin^(-1)\:0,8999026535... \\ \\ 64° ≈ m∠C`

As you can see, the inverse function had to be used towards the end, or the answer would have been thrown off.

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