Position the Line Tangent to the Circle-ის ასლი

The LARGE POINTS, circle, and line are all moveable. Move as many of these objects as you need to make the line TANGENT to the CIRCLE.
In this app below or in the app above, explain why/how you know your line is tangent to the circle.
Same task as above: Position the line tangent to the circle. Yet THIS TIME, make sure the LINE IS NOT HORIZONTAL OR VERTICAL!
In this app below or in the app above, explain why/how you know your line is tangent to the circle in the app above.
Same task as above: Position the line tangent to the circle. Yet THIS TIME, make sure the LINE IS NOT HORIZONTAL OR VERTICAL! Make sure your setup looks ENTIRELY DIFFERENT from the setups you created above!
In this app below or in the app above, explain why/how you know your line is tangent to the circle in the app above.

Information: Position the Line Tangent to the Circle-ის ასლი