如图,已知⊙O上的三点A、B、C,且AB=AC=6cm,BC=10cm(1)求证:∠AOB=∠AOC;(2)求圆片的半径R(结果

2025-05-08 13:39:19
推荐回答(1个)
回答1:

(1)证明:∵AB=AC,
AB
=
AC

∴∠AOB=∠AOC;

(2)设OA交BC于点D,
AB
=
AC

∴OA⊥BC,
∴BD=
1
2
BC=
1
2
×10=5(cm),
∵AB=6cm,
∴在Rt△ABD中,AD=
A B 2 -B D 2
=
11
(cm),
∵OB=Rcm,
则OD=(R-
11
)cm,
∵OB 2 =OD 2 +BD 2
∴R 2 =(R-
11
2 +25,
解得:R=
18
11
11
(cm);

(3)∵3<
11
<4,
∴4<
18
11
11
<6
∴m=6,n=4.