wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

If (2,1) lies on the circle x2+y2+2gx+2fy+c=0 which is concentric with the circle x2+y2+4x6y+3=0, then c is

A
19
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
19
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
21
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
20
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is B 19
The general equation of circle is x2+y2+2mx+2ny+z=0
where,
Center = (m,n)
Radius = m2+n2z

So, For x2+y2+4x6y+3=0,
Center = (2,3)

Since the circles are concentric,
x2+y2+2gx+2fy+c=0
x2+y2+4x6y+c=0

Now, (2,1) lies on x2+y2+4x6y+c=0
4+1+8+6+c=0
c=19

Hence, (B) is the correct answer.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Tangent to a Circle
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon