My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
December 4th, 2006, 02:16 AM   #1
Newbie
 
Joined: Dec 2006

Posts: 9
Thanks: 0

Need help again

A circle of radius,r with its centre in positive quadrant (x>0,y>0) touches both the x and y axes. This circle also touches the line 3x + 4y = 12
Find
A) the two values of r and obtain the equations of the two corresponding circles

B) find the forth equation of the fourth tangent to the circle.

Have problem with the B) part plz help thz in advance.
Grigory_Perelman is offline  
 
December 8th, 2006, 03:53 AM   #2
OHO
Newbie
 
Joined: Dec 2006
From: Rochester, UK

Posts: 17
Thanks: 0

I think the forth tangent is the tangent to bote circles which is the reflection of 3x+4y=12 with respect to the line joining the centers which is y=x. So the the equation of the new tangent is 3y+4x=12 [just change x to y and y to x.]
OHO is offline  
December 19th, 2006, 07:54 AM   #3
Newbie
 
Joined: Dec 2006

Posts: 9
Thanks: 0

Ya, you're right. But do you have any idea to prove it mathemathically???
THZ FOR HELPING
Grigory_Perelman is offline  
Reply

  My Math Forum > High School Math Forum > Algebra


« Cofactors | terms »

Thread Tools
Display Modes






Copyright © 2019 My Math Forum. All rights reserved.