グローバルビジネスで役立つ数学（43）余弦定理で一辺を求める（英語版）

Hi there!

When I became self-employed in my early 30s, I used my apartment as an home-cum-office; however, as the company grew daily through a private concern, I had no choice but to rent an office separately from my home.

I needed a cosigner for renting my office, and one of my overseas business consulting clients willingly agreed to serve as a guarantor. I was happy that we mutually established credibility through its direct investment business.

We had their troubles settled, and I was about to negotiate a contract extension with the client. I was, to be honest, becoming less interested in helping them; to coincide with my reluctance, they started to skimp on consulting fees and canceled being the guarantor for my rent.

Most of my clients regard their consultants as expendable when they gain financial. They easily forget the time when they needed help from consultants.

The trait of the cosigner above considered, today, let me challenge a word problem related to the cosine theorem.

Find the length \(BC (= a)\) for \(△ABC\) with \(AB = 4, CA = 3\) and \(A = 60°\).

Here is my solution to the problem.

\(a^{2} = 4^{2} + 3^{2} – 2・3・4cos60°\)
　\(= 16 + 9 – 24・\frac{1}{2}\)
　\(= 25 – 12\)
　\(= 13\)

Thus, given \(a > 0\), \(a = \sqrt{13}\).

Stay tuned, and expect to see my next post.

Keep well.

Frank Yoshida

￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣
【グローバルビジネスで役立つ数学】でもっと学習する b＾＾)
【参考図書】『もう一度高校数学』（著者：高橋一雄氏）株式会社日本実業出版社
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