Find radius of a circle which is tangent to three known lines I need to find the equation for a circle which is tangent to the following three lines:
y=0
x=0
y=-x+0.338334
For the last tangent line equation, I know that it is tangent at the point (0.169167, 0.169167)
However, for the other two I do not know the exact point of tangency, only that the circle is tangent to the x and y axis. 
Note: Picture is not to scale, only meant to be a reference image


The point must have equal coordinates because the distances to the x-axis and the y-axis must coincide.
So P(u/u)
The distance from the point (0.169167/0.169167) must be u.
So 
$$\sqrt{2}(u-0.169167)=u$$
which gives
$$u=\frac{\sqrt{2}*0.169167}{\sqrt{2}-1} = 0.577572$$
This u is the radius of the desired circle.
