Home » Ask & Discuss » Mathematics. » Analytical Geometry « Back to Discussion



Analytical Geometry

XYZ's Avatar
Hot goIITian

Joined: 18 Jan 2009
Post: 193
9 Mar 2009 02:30:41 IST
0 People liked this
5
444 View Post
Circles
None

If A and B are points in the plane such that PA/PB = k (constant) for all P on a given circle, then the value of k cannot be equal to ________.

 

 

Please give the answer with explanation.


Share this article on:

Comments (5)

XYZ's Avatar

Hot goIITian

Joined: 18 Jan 2009
Posts: 193
9 Mar 2009 10:24:29 IST
0 people liked this

Someone, please reply!!!

kishore subramanian's Avatar

Blazing goIITian

Joined: 21 Apr 2007
Posts: 453
10 Mar 2009 02:16:16 IST
3 people liked this

Let P be a complex number z.

A and B be z1 and z2. PA=|z-z1| , PB=|z-z2|

PA/PB=K

i.e |z-z1|=K|z-z2|   ...

if K=1   then |z-z1|=|z-z2| (use z=x+iy if you dont get my explanation)

which is the equation of perpendicular bisector of the line joining the points A and B.

orher wise it is a circle.

XYZ's Avatar

Hot goIITian

Joined: 18 Jan 2009
Posts: 193
10 Mar 2009 09:12:30 IST
0 people liked this

Thanks a lot Kishore!

A hat from my side.

Vikram Saxena's Avatar

Forum Expert
Joined: 1 Apr 2007
Posts: 3732
11 Mar 2009 00:51:42 IST
2 people liked this

hello dear

 

nice kishore

 

well according to the given condition in the question..that the point lies on the circle

PA = k PB

k can not be equal to 1 bcz .otherwise in this it will the perpendicular bisector of the line joing the point A and B

 

for the equation to be circle:

 

PA = k PB

putting in the algebric from we get:

 

x2 (1-k)  +  y2(1-k)    -   x  (2x1  + 2kx2)  -  y  (2y1  +  2ky2)   +  (x12 + y12   -kx22  - k y22)   =  0

 

hence k can not be equal to 1 for the above equation to be circle

Mr.Nasty ® Retired from Action.'s Avatar

Blazing goIITian

Joined: 16 Jan 2009
Posts: 1041
11 Mar 2009 06:10:10 IST
1 people liked this

k can't be 1.



Quick Reply


Reply

Some HTML allowed.
Keep your comments above the belt or risk having them deleted.
Signup for a avatar to have your pictures show up by your comment
If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team
Free Sign Up!

Preparing for IIT-JEE ?

Arihant Revision Package for IIT JEE - Books, Practice Tests + Rank Predictor


@ INR 1,995/-

For Quick Info

Name

Mobile No.

Find Posts by Topics

Physics.

Topics

Mathematics.

Chemistry.

Biology

Parents

Board

Fun Zone

Sponsored Ads