也試一個幾何解

來源: 於 2024-02-06 20:00:34 [舊帖] [給我悄悄話] 本文已被閱讀：次

Draw diameter AD. Because angle ABC is 45 degrees, so is angle D. Meanwhile, Angle ACD=90 degrees. 
AC = sqrt(16+1)=sqrt(17). Then AD = sqrt(2)*AC= sqrt (34).