drawing arc tangent to 2 curves through a specific tangent point

 From:  pressure (PEER)
11616.1 
How should I draw an arc that's tangent to 2 curves and that passes through a specific point on one of the curves?

Here I want the black circle to be tangent to both the blue line and the red arc and I want the tangent circle to specifically pass through the endpoint of the blue line.

- Peer

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