Hi, could anyone help me with this problem from my engineering design class?

On the left there is the revolving part next to the wall at its normal state. I'm asked to find the distance x (dashed line shown on the right) so that a maximum rotation of 30 degrees is allowed (a pin is supposed to go at the axis of revolution). So I made the sketch on the right and I'm trying to find that circle's radius but I have no idea how to proceed. Only other dimensions are the 40 and 80 shown on the right.
Thanks in advance for any answers.

On the left there is the revolving part next to the wall at its normal state. I'm asked to find the distance x (dashed line shown on the right) so that a maximum rotation of 30 degrees is allowed (a pin is supposed to go at the axis of revolution). So I made the sketch on the right and I'm trying to find that circle's radius but I have no idea how to proceed. Only other dimensions are the 40 and 80 shown on the right.
Thanks in advance for any answers.