第1个回答 2019-06-25
解:
x
+
3y
-
5
=
0,x
+
3y
-
3
=
0
是平行线,
所以圆心在两条直线中间那条平行线上:x
+
3y
-
4
=
0
x
+
3y
=
4
2x
+
y
=
-1
联立得到圆心坐标:x
=
-7/5
,y
=
13/5
圆半径等于两条直线距离之半,注意到斜率
K
=
-1/3
tanA
=
-1/3
(sinA/cosA)^2
=
1/9
9*(sinA)^2
=
(cosA)^2
=
1
-
(sinA)^2
sinA
=
1/√10
R
=
(5
-
3)/2*sinA
=
1/√10
(x
+
7/5)^2
+
(y
-
13/5)^2
=
R^2
圆方程:
(x
+
7/5)^2
+
(y
-
13/5)^2
=
1/10