請教高手九上數學弦心距 詳解 謝謝幫忙?
回答 (1)
2020-11-03 10:35 pm
✔ 最佳答案
∠ACB 是半圓的圓周角, 90°.直徑AB ⊥ 切線BP.
∴BC^2 = BP^2 - CP^2 = 15^2-9^2 = 12^2
設半徑為 r, AC = a. 則
AB^2 = (2r)^2 = BC^2 + AC^2
= 12^2 + a^2
又 (2r)^2 + BP^2 = (AC+CP)^2
∴ (2r)^2 = (a+9)^2 - 15^2
∴ 12^2 + a^2 = (a+9)^2 - 15^2
∴ a = 16
∴ (2r)^2 = 12^2 + 16^2 = 20^2
∴ r = 10
收錄日期: 2021-05-04 02:33:31
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20201103120117AA6ixLT