Coordinate Geometry (1 Viewer)

[leehuan]

Never thought I'd ever need help with a 2U question again. But, oh well. Someone please help.



Please keep answers to within a 2U student's capability. Thanks.

 

[Zlatman]

Since the circle touches both the x-axis and y-axis, and it has radius r, its centre will be (r,r) and its equation (x-r)^2 + (y-r)^2 = r^2 (this is a lot clearer with a diagram). Then we use the perpendicular distance formula from the centre to the tangent, letting the distance equal r. This should give us the radius of the circle, which we substitute into the original equation.

 

[leehuan]

Ahh, I missed the logic in that the centre of the circle must be (r,r). That's why I had 'no point' for the perpendicular distance formula. Makes perfect sense, thanks

 

[Zlatman]

No worries! Glad to help! (My teacher showed me how to do it, haha)