2020-12-05 ■ https://books.google.co.jp/books?id=zP1WDc9DJWIC&pg=PA17&lpg=PA17&dq=curve++++%E7%89%B9%E7%95%B0%E7%82%B9&source=bl&ots=ErizAMRD_W&sig=ACfU3U2bKo0cJniS9xZkkNf2GJJzhqNhoQ&hl=ja&sa=X&ved=2ahUKEwiP1ZyjsPPpAhUUK6YKHfYHAd8Q6AEwB3oECAoQAQ#v=onepage&q=curve%20%20%20%20%E7%89%B9%E7%95%B0%E7%82%B9&f=false