Question 25
As shown in the figure below, circles $C_1,C_2$ of radius $360$ are tangent to each other and both tangent to straight line $\ell$. If circle $C_3$ is tangent to $C_1,C_2,\ell$, and circle $C_4$ is tangent to $C_1,C_3,\ell$, find the radius of $C_4$.
