Why is tangent constraint almost always disabled?

I’m just unable to select the “tangent” constraint no matter what. In the screenshot, I have a line and a circle on the same plane. However when I select the line the “tangent” constraint is disabled in the constraints menu:

Any ideas on what I may be doing wrong?

Secondly, I’m wondering if it’s possible to constraint mid point of a line. I can’t select the mid point, I can only select the end points. Is there a way to make mid point of a line tangent to a circle?

You need to select both sketches, then press the tangent button.

Ah, I thought you select one, then the constrain, then the other… I will try selecting both and see if the constrain button gets enabled.

Could you also look at to my edit? I’m wondering if it’s possible to constraint mid point of a line, instead of end points.

You need to select both sketches, then press the tangent button.

I just tried this but it doesn’t work. I suspect the problem is that the line and the circle are not on the planes. The line is sketched on the “top” plane (across “x”), the circle is on the “front” plane. Could this be the issue?

You can add constraints to sketch elements that are in the same sketch.

Got it, thanks.

What about constraining mid point of a line? (instead of endpoints)