グローバルビジネスで役立つ数学（44）ヘロンの公式（英語版）

Hi there!

My ambition to become a Shousha-man was fostered when I was dating my ex-girlfriend in Himeji Castle in my college days. I can’t figure out how often we had a small picnic inside the castle.

As the Japanese already know as common sense, Himeji Castle is the largest and most visited castle in Japan, and it was registered in 1993 as one of the first UNESCO World Heritage Sites in Japan. The castle is known as “Hakuro-jo” or “Shirasagi-jo” (White Egret Castle or “White Heron Castle) thanks to its brilliant white exterior.

While taking a stroll with her on the site, I used to speak of my dream of proudly becoming a business person traveling worldwide.

――”Negotiating in English is so cool, isn’t it?”
　　When I spoke to her as if I were a full-fledged adult, she infallibly answered,
――”I like you taking great delight in telling your dream.”

So did I when she dimpled mischievously.

The White Heron Castle might have provided me with my incubation period before I flew high in the future. I believe its supposed resemblance to a bird taking flight energized me into a Shousha-man a few years down the road.

Today, instead of calculating the total site area of the castle, I have decided to find the space of a triangle by using “Heron’s formula.”

Find the area \(S\) of \(\Delta ABC\) providing \(a = 4, b = 5\), and \(c = 6\).

By using Heron’s formula, \(2s = 4 + 5 + 6\), thus \(s = \frac{15}{2}\).
Therefore,

\(S = \sqrt{s(s – a)(s – b)(s – c)}\)
\(=\sqrt{\frac{15}{2}・\frac{7}{2}・\frac{5}{2}・\frac{3}{2}}\)
\(= \frac{15\sqrt{7}}{4}\)

――”I wanna be a hero, not heron for you, you know.”
　　She giggled.

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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