Tardigrade
Tardigrade - CET NEET JEE Exam App
Exams
Login
Signup
Tardigrade
Question
Mathematics
The number of common tangents that can be drawn to the circle x2+y2-4 x-6 y-3=0 and x2+y2+2 x+2 y+1=0 is
Q. The number of common tangents that can be drawn to the circle
x
2
+
y
2
−
4
x
−
6
y
−
3
=
0
and
x
2
+
y
2
+
2
x
+
2
y
+
1
=
0
is
1461
215
Conic Sections
Report Error
A
1
B
2
C
3
D
4
Solution:
The two circles are
x
2
+
y
2
−
4
x
−
6
y
−
3
=
0
and
x
2
+
y
2
+
2
x
+
2
y
+
1
=
0
Center :
C
1
≡
(
2
,
3
)
,
C
2
≡
(
−
1
,
−
1
)
radii :
r
1
=
4
,
r
2
=
1
We have
C
1
C
2
=
5
=
r
1
+
r
2
, therefore there are 3 common tangents to the given circles.