GWD3-8

[Emilyh]

In the figure shown, the triangle is inscribed in the semicircle. If the length of line segment AB is 8 and the length of line segment BC is 6, what is the length of arc ABC?

A. 15
B. 12
C. 10
D. 7
E. 5

Ans:E

請問爲何是E呢?

[FrankChang]

可以給圖嗎?又是什麼意思?!

[Emilyh]

不好意思，我忘記附圖了。
想請問這樣列式對嗎?

AC^2=AB^2+BC^2=8^2+6^2=100
AC=10

2r拍=10
2r拍X180/360(ABC所對角度)
=10拍X1/2
=5拍

謝謝

[FrankChang]

okay囉~
知道半圓=>角ABC必為90度,
知道半徑再求弧長(半圓弧長又剛好是圓週長一半)