Help with tricky tangent line drawing

[a_pilger]

Hey guys,

I'm new here, so apologize me for anything silly I might do/say.

I'm facing a very tricky tangent problem which I do not know how to solve. I have one point, one line and one circle with the radius of 3. I need to move the circle along the line in a manner which the exact tangent point of a line between the point and the circle intersects with another line.

It's hard to explain with words, so I guess I'll just attach a file so you guys can check it out.

Any help would me most appreciated!

Edit:

Here's an image for better visualization:

[sthompson1021 · Accepted solution]

Is this what your looking for?

[dmfrazier · Accepted solution]

It looks like you've already done what you describe (but maybe I have misunderstood).

Is it that you need to figure out how the view on the left became the view on the right?

Here's one (relatively straightforward) possibility:

1. Draw a line from center of circle to the upper intersection of circle and left parallel line.

2. Offset that line (to the left), using the Through option, and selecting your fixed point (snap to node) as the through point.

3. Draw a line between any two common points (endpoints,midpoint) of those lines.

4. Offset that line as in step 2.

5. Extend that line (if you wish) to the right parallel line.

This gives you two possible points to use for moving the circle.

There are alternative ways using UCS or object snap tracking settings, too.

[hwalker]

I would draw a line from the fixed point to your straight lines using the PERPENDICULAR osnap.

I would then move the circle using the INTERSECTION osnap for the basepoint and the destination.

[a_pilger]

Hey guys!

Thanks for the quick responses! Muchly appreciated.

The solution suggested by hwalker didn't quite work because the desired tangent isn't perpendicular to the parallel lines, but both methods from thompson and frazier worked great. The detail was in front of me and I couldn't see. after making that first line which defined where was the tangent on the circl, it was all clear to me.

Many thanks for the help!