Question

Find the equation of the circle whose center on the line y = x, tanget to the line y =5, and has radius 2. Someone please? :)

Answer 1

ok if it is on the line y = x you know the center is (a,a) i.e same number in both coordinate yes?

Answer 2

I see..

Answer 3

and you know the radius is 2 so equation looks like
\[(x-a)^2+(y-a)^2=4\]

Answer 4

What does tangent to the line ... mean?

Answer 5

ahh touches at one point and doesn't cross

Answer 6

Oooo I see..

Answer 7

http://www.google.com/imgres?imgurl=http://ef004.k12.sd.us/ch10no17.gif&imgrefurl=http://ef004.k12.sd.us/ch10notes.htm&h=265&w=392&sz=4&tbnid=p1yHea7Z_8twNM:&tbnh=78&tbnw=115&prev=/search%3Fq%3Dline%2Btangent%2Bto%2Bcircle%2Bimage%26tbm%3Disch%26tbo%3Du&zoom=1&q=line+tangent+to+circle+image&usg=__7Vd4OlPKRTWwKijqAqmR137PxLw=&sa=X&ei=YiMLToOfGqjo0QGps-CNAQ&ved=0CBsQ9QEwAA&dur=453

Answer 8

ok i bet that didn't work hold on

Answer 9

I saw the illustration. :)

Answer 10

ok so distance between (a,a) and (a,5) is 2 so you can solve for a